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Sample records for external forces acting

  1. Significance of Neglected Hydrodynamic Forces on the Motion of Submerged Particles Acted on by External Body Forces

    Science.gov (United States)

    Cooper, Daniel; Charonko, John; Vlachos, Pavlos

    2011-11-01

    Recently, the manipulation of submerged particles using electromagnetic body forces has drawn increasing interest from a variety of fields, particularly medicine, where electrophoretic manipulation in lab-on-a-chip applications and magnetic drug targeting have become important areas of interest. As a direct result of this increasing interest a large number of simulations have been performed investigating the performance of devices and systems whose operation is based upon these physics. In the vast majority of cases, these simulations are based upon a force balance of the applicable body force and Stokes drag. Such simulations neglect additional hydrodynamic forces, including the added mass, Basset, Saffman, and Magnus forces. In the current study, the full equations of motion containing all of the aforementioned terms are nondimensionalized leading to a set of nondimensional parameters governing the behavior of the particle. A parametric investigation is then performed by calculating particle trajectories for both Poiseuille and Womersley flows. This analysis reveals that in many cases, the forces neglected in previous simulations are significant and should not be neglected in future studies.

  2. Internal and External Forces in Language Change.

    Science.gov (United States)

    Yang, Charles D.

    2000-01-01

    Develops a model of language change characterizing the dynamic interaction between internal universal grammar and external linguistic evidence, as mediated by language acquisition. Borrows insights from the study of biological evolution, where internal and external forces interact in similar fashion. Applies the model to explore the loss of the…

  3. The Research and Development of the External Magnetic Field Acting on Electro-Deposition Process

    OpenAIRE

    Wu Menghua; Jia Weiping

    2016-01-01

    The research and development status of the electro-deposition technology under the action of external magnetic field are introduced. The basic characteristics and applied manners of external magnetic field in electro-deposition process are summarized. The acting principle of external magnetic field, the effects of magnetic hydrodynamics (MHD) caused by the Lorentz force, and the acting of magnetic force on the metal ions and particles are described. The main actions of external magnetic field...

  4. Synchronization of cardiorhythm by weak external forcing

    Directory of Open Access Journals (Sweden)

    V. S. Anishchenko

    2000-01-01

    Full Text Available We study the possibility to synchronize cardiorhythm of a human by periodic and aperiodic sequences of light and sound pulses. Aperiodic forcing is defined by variation of RR intervals of another subject. Phase locking between cardiorhythm and weak external forcing is detected on finite time intervals. We observe the 1:1 synchronization for periodic forcing and n:m synchronization for aperiodic one.

  5. EXTERNAL BODY FORCE IN FINITE DIFFERENCE LATTICE BOLTZMANN METHOD

    Institute of Scientific and Technical Information of China (English)

    CHEN Sheng; LIU Zhao-hui; SHI Bao-chang; ZHENG Chu-guang

    2005-01-01

    A new finite difference lattice Boltzmann scheme is developed. Because of analyzing the influence of external body force roundly, the correct Navier-Stokes equations with the external body force are recovered, without any additional unphysical terms. And some numerical results are presented. The result which close agreement with analytical data shows the good performance of the model.

  6. Equatorial Rossby Solitary Wave Under the External Forcing

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Kuo; LIU Shi-Da

    2005-01-01

    A simple shallow-water model with influence of external forcing on a β-plane is applied to investigate the nonlinear equatorial Rossby waves in a shear flow. By the perturbation method, the extended variable-coefficient KdV equation under an external forcing is derived for large amplitude equatorial Rossby wave in a shear flow. And then various periodic-like structures for these equatorial Rossby waves are obtained with the help of Jacobi elliptic functions.It is shown that the external forcing plays an important role in various periodic-like structures.

  7. Response of Brownian Fluctuations to External Forces

    Science.gov (United States)

    Laub, Jeffrey William

    Millikan's law of particle fall is an empirical result which shows the dependence of particle fall rate in a gas on particle radius and host gas density. The size of submicron particles in gases has long been determined by Millikan's law. The dominant factor is Stokes' law with a correction added to account for the physics of slip. However, it was recently shown by Kim and Fedele that Brownian fluctuations affect the fall rate while showing no anomalies in the density dependence of the rms displacement. The effect was an enhancement of the fall rate of small particles as the density of the host gas is increased. This enhancement showed a size dependence in the form of a smooth transition from the one of decreasing fall rate with increasing density for large particles (~0.4 μm radius) to another of increasing fall rate with increasing gas density for small particles ( ~0.15mum radius). The magnitude of the anomaly is determined by how the rms Brownian velocity compares with its fall rate. In an effort to understand the effect of Brownian fluctuations coupling with gravity, a new experiment has been carried out where an AC field was applied to force particles to fluctuate more in the vertical direction on one hand and where a constant DC field was applied to change the effective force of gravity on the other. These fields were applied to a charged oil drop in the 0.2 to 0.3 μm radius range falling in a nitrogen environment. Displacements over a 4 second time interval were repeatedly measured in both the vertical and horizontal directions. The original experimental apparatus was used with some modifications. The modifications included computer automation of particle control and data taking to allow for longer use of the same particle, up to 120 hours, and to facilitate application of the additional fields. The objective was to make large particles appear to be smaller via forced oscillations and make them fall faster or slower via the DC bias to effect the change in

  8. EEO External Relevant Labor Force Analysis

    Science.gov (United States)

    1980-09-01

    less than 500 new hires, a percentage (35, 50 or 100% depending on required sample sizes) of the total Navy work force in an area was included in the...Francisco-Alameda CA 808 Pearl Harbor HI 809 Vallejo CA 810 Long Beach CA 811 Port Hueneme CA 817 China Lake CA 824 Corona CA 826 San Mateo CA 828 San...4 wl~w OrO 000 @0 00 @00O0 09-r mom n Of arn cc @e @000 LI c r-rw crm C4 Z ft W94 1 cw*0 O&c C - ~0 I-C 64 006 Icnf SO c m Iam )- 0 4 5 I

  9. Forces acting in quasi 2d emulsions

    Science.gov (United States)

    Orellana, Carlos; Lowensohn, Janna; Weeks, Eric

    We study the forces in a quasi two dimensional emulsion system. Our samples are oil-in-water emulsions confined between two close-spaced parallel plates, so that the oil droplets are deformed into pancake shapes. By means of microscopy, we measure the droplet positions and their deformation, which we can relate to the contact forces due to surface tension. We improve over prior work in our lab, achieving a better force resolution. We use this result to measure and calibrate the viscous forces acting in our system, which fully determine all the forces on the droplets. Our results can be applied to study static configurations of emulsion, as well as faster flows.

  10. Stability of GOY Model Under Modulation of Periodic External Force

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ying-Kui; CHEN Shi-Gang; WANG Guang-Rui

    2008-01-01

    There is a phase transition between quasi-periodic state and intermittent chaos in GOY model with a critical value δ0. When we add a modulated periodic external force to the system, the phase transition can also be found with a critical value δe. Due to coupling between the force and the intrinsic fluctuation of the velocity on shells in GOY model, the stability of the system has been changed, which results in the variation of the critical value. For proper intensity and period of the force, δe is unequal to δ0. The critical value is a nonlinear function of amplitude of the force, and the fluctuation of the velocity can resonate with the external force for certain period Te.

  11. The Research and Development of the External Magnetic Field Acting on Electro-Deposition Process

    Directory of Open Access Journals (Sweden)

    Wu Menghua

    2016-01-01

    Full Text Available The research and development status of the electro-deposition technology under the action of external magnetic field are introduced. The basic characteristics and applied manners of external magnetic field in electro-deposition process are summarized. The acting principle of external magnetic field, the effects of magnetic hydrodynamics (MHD caused by the Lorentz force, and the acting of magnetic force on the metal ions and particles are described. The main actions of external magnetic field include MHD effect, magnetizing force, affecting the physical and chemical properties of the bath, affecting the disperse ability and coverage capacity of bath, affecting the mass transfer process of electro-deposition, affecting the chemical reaction process and current distribution of electrode surface. Some examples of electro-depositing single metal coatings, alloy coatings and composite coatings under action of magnetic field are explained. During the electro-depositing process, the external magnetic field has different degrees of impact on solution properties, mass transfer, charge transfer, content of composited nanoparticles, crystal growth and crystal orientation etc. The specific impact of magnetic field during the electro-depositing is also classified and summarized. The problems that existed in electro-deposition process while applying magnetic field and the next development trend were summarized.

  12. Manipulating single enzymes by an external harmonic force

    DEFF Research Database (Denmark)

    Lomholt, Michael A; Urbakh, Michael; Metzler, Ralf

    2007-01-01

    We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme...

  13. External Force Estimation for Teleoperation Based on Proprioceptive Sensors

    Directory of Open Access Journals (Sweden)

    Enrique del Sol

    2014-03-01

    Full Text Available This paper establishes an approach to external force estimation for telerobotic control in radioactive environments by the use of an identified manipulator model and pressure sensors, without employing a force/torque sensor. The advantages of - and need for - force feedback have been well-established in the field of telerobotics, where electrical and back-drivable manipulators have traditionally been used. This research proposes a methodology employing hydraulic robots for telerobotics tasks based on a model identification scheme. Comparative results of a force sensor and the proposed approach using a hydraulic telemanipulator are presented under different conditions. This approach not only presents a cost effective solution but also a methodology for force estimation in radioactive environments, where the dose rates limit the use of electronic devices such as sensing equipment.

  14. Power, muscular work, and external forces in cycling.

    Science.gov (United States)

    de Groot, G; Welbergen, E; Clijsen, L; Clarijs, J; Cabri, J; Antonis, J

    1994-01-01

    Cycling performance is affected by the interaction of a number of variables, including environment, mechanical, and human factors. Engineers have focused on the development of more efficient bicycles. Kinesiologists have examined cycling performance from a human perspective. This paper summarizes only certain aspects of human ergonomics of cycling, especially those which are important for the recent current research in our departments. Power is a key to performance of physical work. During locomotion an imaginary flow of energy takes place from the metabolism to the environment, with some efficiency. The 'useful' mechanical muscle power output might be used to perform movements and to do work against the environment. The external power is defined as the sum of joint powers, each calculated as the product of the joint (net) moment and angular velocity. This definition of external power is closely related to the mean external power as applied to exercise physiology: the sum of joint powers reflects all mechanical power which in principle can be used to fulfil a certain task. In this paper, the flow of energy for cycling is traced quantitatively as far as possible. Studies on the total lower limb can give insight into the contribution of individual muscles to external power. The muscle velocity (positive or negative) is obtained from the positions and orientations of body segments and a bar linkage model of the lower limb. The muscle activity can be measured by electromyography. In this way, positive and negative work regions in individual muscles are identified. Synergy between active agonistic/antagonistic muscle groups occurs in order to deliver external power. Maximum power is influenced by body position, geometry of the bicycle and pedalling rate. This has to be interpreted in terms of the length-tension and force-velocity-power relationships of the involved muscles. Flat road and uphill cycling at different saddle-tube angles is simulated on an ergometer. The

  15. Real-Time Control of Humanoid Robots Considering External Forces on Upper Part of the Body

    Science.gov (United States)

    Inomata, Kentaro; Shigemori, Yo; Uchimura, Yutaka

    Recently, the demand for the practical use of service robots has risen significantly because of acceleration of demographic aging, and a humanoid robot is one of the promising form factors of service robots. When a humanoid robot is used by a human in a real environment, the robot needs to be designed by taking into account the various external forces that act on the robot. Thus far, most of the walking humanoid robots have been mainly controlled by the conventional ZMP method to maintain a stable walking posture. However, the conventional ZMP method can not be used to handle the various external forces that act on the upper part of the humanoid robot body. To overcome these problems, in this paper, we propose a novel control method, which we called 3DZMP and pZMP, for a humanoid robot to react to the external force on the upper part of the body. The 3DZMP is defined as the point in three-dimensional space at which the moment about all axes is zero. 3DZMP can prevent the rotation of a humanoid robot. The pZMP is defined as the point corresponding to the orthographic projection of the 3DZMP on a plane. pZMP is used to evaluate the stability of 3DZMP. We implemented the proposed method on a prototype robot and verified that the robot gained the capability to react to external forces that could not be handled by the conventional ZMP method.

  16. Atlantic Meridional Overturning Circulation response to idealized external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Park, W.; Latif, M. [Leibniz-Institut fuer Meereswissenschaften an der Universitaet Kiel, Kiel (Germany)

    2012-10-15

    The response of the Atlantic Meridional Overturning Circulation (AMOC) to idealized external (solar) forcing is studied in terms of the internal (unforced) AMOC modes with the Kiel Climate Model (KCM), a coupled atmosphere-ocean-sea ice general circulation model. The statistical investigation of KCM's internal AMOC variability obtained from a multi-millennial control run yields three distinct modes: a multi-decadal mode with a period of about 60 years, a quasi-centennial mode with a period of about 100 years and a multi-centennial mode with a period of about 300-400 years. Most variance is explained by the multi-centennial mode, and the least by the quasi-centennial mode. The solar constant varies sinusoidally with two different periods (100 and 60 years) in forced runs with KCM. The AMOC response to the external forcing is rather complex and nonlinear. It involves strong changes in the frequency structure of the variability. While the control run depicts multi-timescale behavior, the AMOC variability in the experiment with 100 year forcing period is channeled into a relatively narrow band centered near the forcing period. It is the quasi-centennial AMOC mode with a period of just under 100 years which is excited, although it is heavily damped in the control run. Thus, the quasi-centennial mode retains its period which does not correspond exactly to the forcing period. Surprisingly, the quasi-centennial mode is also most strongly excited when the forcing period is set to 60 years, the period of the multi-decadal mode which is rather prominent in the control run. It is largely the spatial structure of the forcing rather than its period that determines which of the three internal AMOC modes is excited. The results suggest that we need to understand the full modal structure of the internal AMOC variability in order to understand the circulation's response to external forcing. This could be a challenge for climate models: we cannot necessarily expect that the

  17. Ratchet effect on a relativistic particle driven by external forces

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, Niurka R [Departamento de Fisica Aplicada I, Escuela Universitaria Politecnica, Universidad de Sevilla, Calle Virgen de Africa 7, E-41011 Sevilla (Spain); Alvarez-Nodarse, Renato [Departamento de Analisis Matematico, Facultad de Matematicas, Universidad de Sevilla, Apdo 1160, E-41080 Sevilla (Spain); Cuesta, Jose A, E-mail: niurka@us.es, E-mail: ran@us.es, E-mail: cuesta@math.uc3m.es [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes, Madrid (Spain)

    2011-10-21

    We study the ratchet effect of a damped relativistic particle driven by both asymmetric temporal bi-harmonic and time-periodic piecewise constant forces. This system can be formally solved for any external force, providing the ratchet velocity as a nonlinear functional of the driving force. This allows us to explicitly illustrate the functional Taylor expansion formalism recently proposed for this kind of systems. The Taylor expansion reveals particularly useful to obtain the shape of the current when the force is periodic, piecewise constant. We also illustrate the somewhat counterintuitive effect that introducing damping may induce a ratchet effect. When the force is symmetric under time-reversal and the system is undamped, under symmetry principles no ratchet effect is possible. In this situation increasing damping generates a ratchet current which, upon increasing the damping coefficient eventually reaches a maximum and decreases toward zero. We argue that this effect is not specific of this example and should appear in any ratchet system with tunable damping driven by a time-reversible external force. (paper)

  18. Manipulating single enzymes by an external harmonic force

    DEFF Research Database (Denmark)

    Lomholt, Michael A; Urbakh, Michael; Metzler, Ralf

    2007-01-01

    We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme......, thereby controlling the enzymatic activity (i.e., product formation). This analysis demonstrates that it is, in principle, possible to obtain information about particular rates within the kinetic scheme....

  19. 75 FR 70160 - Affordable Care Act; Federal External Review Process; Request for Information

    Science.gov (United States)

    2010-11-17

    ... Administration 29 CFR Part 2590 Affordable Care Act; Federal External Review Process; Request for Information... Act, as amended by the Affordable Care Act, and its implementing regulations. DATES: Submit written or... and external review processes under the Affordable Care Act; those comments are being collected...

  20. Numerical studies of a plasma diode with external forcing

    Science.gov (United States)

    Rekaa, V. L.; Pécseli, H. L.; Trulsen, J. K.

    2012-08-01

    With reference to laboratory Q-machine studies we analyze the dynamics of a plasma diode under external forcing. Assuming a strong axial magnetic field, the problem is analyzed in one spatial dimension by a particle-in-cell code. The cathode is assumed to be operated in electron rich conditions, supplying an abundance of electrons. We compare different forcing schemes with the results obtained by solving the van der Pol equation. In one method of forcing we apply an oscillation in addition to the DC end plate bias and consider both amplitude and frequency variations. An alternative method of perturbation consists of modelling an absorbing grid at some internal position. Also in this case we can have a constant frequency with varying amplitude or alternatively an oscillation with chirped frequency but constant amplitude. We find that the overall features of the forced van der Pol equation are recovered, but the details in the plasma response need more attention to the harmonic responses, requiring extensions of the model equation. The analysis is extended by introducing collisional effects, where we emphasize charge exchange collisions of ions, since these processes usually have the largest cross sections and give significant modifications of the diode performance. In particular we find a reduction in oscillator frequency, although a linear scaling of the oscillation time with the system length remains also in this case.

  1. Entropic stochastic resonance without external force in oscillatory confined space

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics and Hefei National Laboratory for Physical Sciences at Microscales, iChEM, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-05-21

    We have studied the dynamics of Brownian particles in a confined geometry of dumbbell-shape with periodically oscillating walls. Entropic stochastic resonance (ESR) behavior, characterizing by a maximum value of the coherent factor Q at some optimal level of noise, is observed even without external periodic force in the horizontal direction, which is necessary for conventional ESR where the wall is static and the particle is subjected to the force. Interestingly, the ESR can be remarkably enhanced by the particle gravity G, in contrast to the conventional case. In addition, Q decreases (increases) with G in the small (large) noise limit, respectively, while it non-monotonically changes with G for moderate noise levels. We have applied an effective 1D coarsening description to illustrate such a nontrivial dependence on G, by investigating the property of the 1D effective potential of entropic nature and paying special attention to the excess part resulting from the boundary oscillation. Dependences of the ESR strength with other related parameters are also discussed.

  2. Hydrodynamic Forces on Macromolecules Protruding from Lipid Bilayers Due to External Liquid Flows.

    Science.gov (United States)

    Jönsson, Peter; Jönsson, Bengt

    2015-11-24

    It has previously been observed that an externally applied hydrodynamic shear flow above a fluid lipid bilayer can change the local concentration of macromolecules that are associated with the lipid bilayer. The external liquid flow results in a hydrodynamic force on molecules protruding from the lipid bilayer, causing them to move in the direction of the flow. However, there has been no quantitative study about the magnitude of these forces. We here use finite element simulations to investigate how the magnitude of the external hydrodynamic forces varies with the size and shape of the studied macromolecule. The simulations show that the hydrodynamic force is proportional to the effective hydrodynamic area of the studied molecule, Ahydro, multiplied by the mean hydrodynamic shear stress acting on the membrane surface, σhydro. The parameter Ahydro depends on the size and shape of the studied macromolecule above the lipid bilayer and scales with the cross-sectional area of the molecule. We also investigate how hydrodynamic shielding from other surrounding macromolecules decreases Ahydro when the surface coverage of the shielding macromolecules increases. Experiments where the protein streptavidin is anchored to a supported lipid bilayer on the floor of a microfluidic channel were finally performed at three different surface concentrations, Φ = 1%, 6%, and 10%, where the protein is being moved relative to the lipid bilayer by a liquid flow through the channel. From photobleaching measurements of fluorescently labeled streptavidin we found the experimental drift data to be within good accuracy of the simulated results, less than 12% difference, indicating the validity of the results obtained from the simulations. In addition to giving a deeper insight into how a liquid flow can affect membrane-associated molecules in a lipid bilayer, we also see an interesting potential of using hydrodynamic flow experiments together with the obtained results to study the size and

  3. Determination of External Forces in Alpine Skiing Using a Differential Global Navigation Satellite System

    Directory of Open Access Journals (Sweden)

    Erich Müller

    2013-08-01

    Full Text Available In alpine ski racing the relationships between skier kinetics and kinematics and their effect on performance and injury-related aspects are not well understood. There is currently no validated system to determine all external forces simultaneously acting on skiers, particularly under race conditions and throughout entire races. To address the problem, this study proposes and assesses a method for determining skier kinetics with a single lightweight differential global navigation satellite system (dGNSS. The dGNSS kinetic method was compared to a reference system for six skiers and two turns each. The pattern differences obtained between the measurement systems (offset ± SD were −26 ± 152 N for the ground reaction force, 1 ± 96 N for ski friction and −6 ± 6 N for the air drag force. The differences between turn means were small. The error pattern within the dGNSS kinetic method was highly repeatable and precision was therefore good (SD within system: 63 N ground reaction force, 42 N friction force and 7 N air drag force allowing instantaneous relative comparisons and identification of discriminative meaningful changes. The method is therefore highly valid in assessing relative differences between skiers in the same turn, as well as turn means between different turns. The system is suitable to measure large capture volumes under race conditions.

  4. Role of external magnetic field and current closure in the force balance mechanism of a magnetically stabilized plasma torch

    Science.gov (United States)

    G, Ravi; Goyal, Vidhi

    2012-10-01

    Experimental investigations on the role of applied external magnetic field and return current closure in the force balance mechanism of a plasma torch are reported. The plasma torch is of low power and has wall, gas and magnetic stabilization mechanisms incorporated in it. Gas flow is divided into two parts: axial-central and peripheral-shroud, applied magnetic field is axial and return current is co-axial. Results indicate that application of large external magnetic field gives rise to not only J x B force but also, coupled with gas flow, to a new drag-cum-centrifugal force that acts on the plasma arc root and column. The magnetic field also plays a role in the return current closure dynamics and thus in the overall force balance mechanism. This in turn affects the electro-thermal efficiency of the plasma torch. Detailed experimental results, analytical calculations and physical model representing the processes will be presented and discussed.

  5. External force estimation and implementation in robotically assisted minimally invasive surgery.

    Science.gov (United States)

    Sang, Hongqiang; Yun, Jintian; Monfaredi, Reza; Wilson, Emmanuel; Fooladi, Hadi; Cleary, Kevin

    2017-06-01

    Robotically assisted minimally invasive surgery can offer many benefits over open surgery and laparoscopic minimally invasive surgery. However, currently, there is no force sensing and force feedback. This research was implemented using the da Vinci research kit. An external force estimation and implementation method was proposed based on dynamics and motor currents. The dynamics of the Patient Side Manipulator was modeled. The dynamic model was linearly parameterized. The estimation principle of external force was derived. The dynamic parameters were experimentally identified using a least squares method. Several experiments including dynamic parameter identification, joint torque estimation, and external force estimation were performed. The results showed that the proposed method could implement force estimation without using a force sensor. The force estimation method was proposed and implemented and experimental results showed the method worked and was feasible. This method could be used for force sensing in minimally invasive surgical robotics in the future. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Acoustic Force Density Acting on Inhomogeneous Fluids in Acoustic Fields

    DEFF Research Database (Denmark)

    Karlsen, Jonas Tobias; Augustsson, Per; Bruus, Henrik

    2016-01-01

    We present a theory for the acoustic force density acting on inhomogeneous fluids in acoustic fields on time scales that are slow compared to the acoustic oscillation period. The acoustic force density depends on gradients in the density and compressibility of the fluid. For microfluidic systems...

  7. Investigation of Multiscale Non-equilibrium Flow Dynamics Under External Force Field

    CERN Document Server

    Xiao, Tianbai

    2016-01-01

    The multiple scale non-equilibrium gaseous flow behavior under external force field is investigated. Both theoretical analysis based on the kinetic model equation and numerical study are presented to demonstrate the dynamic effect of external force on the flow evolution, especially on the non-equilibrium heat flux. The current numerical experiment is based on the well-balanced unified gas-kinetic scheme (UGKS), which presents accurate solutions in the whole flow regime from the continuum Navier-Stokes solution to the transition and free molecular ones. The heat conduction in the non-equilibrium regime due to the external forcing term is quantitatively investigated. In the lid-driven cavity flow study, due to the external force field the density distribution inside cavity gets stratified and a multiscale non-equilibrium flow transport appears in a single gas dynamic system. With the increment of external forcing term, the flow topological structure changes dramatically, and the temperature gradient, shearing s...

  8. Transient Dynamics of Elastic Hele-Shaw Cell Due to External Forces with Application to Impulse Mitigation

    CERN Document Server

    Tulchinsky, Arie

    2015-01-01

    We study the transient dynamics of a viscous liquid contained in a narrow gap between a rigid surface and a parallel elastic plate. The elastic plate is deformed due to an externally applied time-varying pressure-field. We model the flow-field via the lubrication approximation, and the plate deformation by the Kirchhoff-Love plate theory. We obtain a self-similarity solution for the case of an external point force acting on the elastic plate. The pressure and deformation field during and after the application of the external force are derived and presented by closed form expressions. We examine a uniform external pressure acting on the elastic plate over a finite region and during a finite time period, similar to the viscous-elastic interaction time-scale. The interaction between elasticity and viscosity is shown to reduce by order of magnitude the pressure within the Hele-Shaw cell compared with the externally applied pressure, thus suggesting such configurations may be used for impact mitigation.

  9. Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

    Directory of Open Access Journals (Sweden)

    Luning Shi

    2014-01-01

    Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

  10. Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis.

    Science.gov (United States)

    Curtin, Maurice; Lowery, Madeleine M

    2014-04-07

    This study uses biomechanical modelling and computational optimization to investigate muscle activation in combination with applied external forces as a treatment for scoliosis. Bracing, which incorporates applied external forces, is the most popular non surgical treatment for scoliosis. Non surgical treatments which make use of muscle activation include electrical stimulation, postural control, and therapeutic exercises. Electrical stimulation has been largely dismissed as a viable treatment for scoliosis, although previous studies have suggested that it can potentially deliver similarly effective corrective forces to the spine as bracing. The potential of muscle activation for scoliosis correction was investigated over different curvatures both with and without the addition of externally applied forces. The five King's classifications of scoliosis were investigated over a range of Cobb angles. A biomechanical model of the spine was used to represent various scoliotic curvatures. Optimization was applied to the model to reduce the curves using combinations of both deep and superficial muscle activation and applied external forces. Simulating applied external forces in combination with muscle activation at low Cobb angles (forces were applied in combination, lower levels of muscle activation or less external force was required to reduce the curvature of the spine, when compared with either muscle activation or external force applied in isolation. The results of this study suggest that activation of superficial and deep muscles may be effective in reducing spinal curvature at low Cobb angles when muscle groups are selected for activation based on the curve type. The findings further suggest the potential for a hybrid treatment involving combined muscle activation and applied external forces at larger Cobb angles.

  11. A study on forces acting on a flapping wing

    Directory of Open Access Journals (Sweden)

    Cetiner O.

    2013-04-01

    Full Text Available In order to study the forces acting on a flapping wing, an experimental investigation is performed in steady water flow. In this study, a SD7003 airfoil undergoes combined pitching and plunging motion which simulates the forward flight of small birds. The frequency of pitching motion is equal to the frequency of plunging motion and pitch leads the plunge by a phase angle of 90 degrees. The experiments are conducted at Reynolds numbers of 2500 ≤ Re ≤ 13700 and the vortex formation is recorded using the digital particle image velocimetry (DPIV technique. A prediction of thrust force and efficiency is calculated from the average wake deficit of DPIV data, the near-wake vorticity patterns and time dependent velocity vectors are determined to comment on the thrust and drag indication. Direct force measurements are attempted using a Force/Torque sensor which is capable of measuring forces and moments in three axial directions.

  12. UNIFORM ATTRACTOR FOR NONAUTONOMOUS INCOMPRESSIBLE NON-NEWTONIAN FLUID WITH A NEW CLASS OF EXTERNAL FORCES

    Institute of Scientific and Technical Information of China (English)

    Zhao Caidi; Jia Xiaolin; Yang Xinbo

    2011-01-01

    This paper is joint with [27].The authors prove in this article the existence and reveal its structure of uniform attractor for a two-dimensional nonautonomous incompressible non-Newtonian fluid with a new class of external forces.

  13. Spatiotemporal complexity of a predator-prey system with the effect of noise and external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Rao Feng [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China); Wang Weiming [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China)], E-mail: weimingwang2003@163.com; Li Zhenqing [Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093 (China)

    2009-08-30

    In this paper, we present a spatial version of the Ivlev-type predator-prey model which contains some important factors, such as noise on predator, external periodic forcing and diffusion processes on both predator and prey. From the numerical results, we know that noise or external periodic forcing can induce instability and enhance the oscillation of the species density, and the cooperation between noise and external periodic forcing inherent to the deterministic dynamics of periodically driven models gives rise to the appearance of a rich transport phenomenology. Furthermore, we demonstrate that the spatially extended system exhibits a resonant patterns and frequency-locking phenomena. Our results show that noise and external periodic forcing play a prominent role in the predator-prey model.

  14. EXISTENCE OF INFINITE ENERGY SOLUTION TO THE INELASTIC BOLTZMANN EQUATION WITH EXTERNAL FORCE

    Institute of Scientific and Technical Information of China (English)

    Wei Jinbo; Zhang Xianwen

    2012-01-01

    In this paper,the Cauchy problem for the inelastic Boltzmann equation with external force is considered in the case of initial data with infinite energy.More precisely,under the assumptions on the bicharacteristic generated by external force,we prove the global existence of solution for small initial data compared to the local Maxwellian exp{-p|x-v|2},which has infinite mass and energy.

  15. Recent drying of the Fertile Crescent: natural or externally forced?

    Science.gov (United States)

    Kelley, Colin

    2014-05-01

    There has been a reduction in observed precipitation over the greater Mediterranean region since the middle of the 20th Century. Recent studies suggest that while anthropogenic forcing has already begun to assert itself in recent decades, the preponderance of the winter drying trend is attributable to the large natural multidecadal variability of the North Atlantic Oscillation (NAO), while over the eastern Mediterranean, the anthropogenic, or forced drying signal is more clearly evident. This forced drying is projected to increase during the 21st Century according to the newest global climate models and this aridification would present significant challenges for a region that is already water-stressed. Although the Fertile Crescent is historically known for its agricultural prosperity, the severity and persistence of the recent multiyear drought in Syria, directly prior to the 2011 uprising there, leads us to ask whether this is evidence of emerging global warming influence. This drought exacerbated existing water insecurity, resulting in an agricultural collapse and a mass migration of rural drought refugees to the urban areas in Syria's west. This migration followed the previous influx of Iragi refugees and combined with strong natural population growth to place a severe strain on resources. Here we examine observations of precipitation and temperature, both gridded and stations, along with simulations and projections from the newest global climate models, to estimate the forced contribution to the recent Syrian drought, and assess the uncertainty in future drying according to the models. We find that this region has experienced a long-term downward trend in precipitation, and a concomitant increase in temperature, serving to further dry the soil, and in surface pressure. We find that the shift in the distributions of three-year running means of surface pressure and precipitation due to the forcing make severe events such as the recent Syrian drought several

  16. Vertical force acting on partly submerged spindly cylinders

    Directory of Open Access Journals (Sweden)

    Xinbin Zhang

    2014-04-01

    Full Text Available When an object is placed on a water surface, the air-water interface deforms and a meniscus arises due to surface tension effects, which in turn produces a lift force or drag force on the partly submerged object. This study aims to investigate the underlying mechanism of the vertical force acting on spindly cylinders in contact with a water surface. A simplified 2-D model is presented, and the profile of the curved air-water interface and the vertical force are computed using a numerical method. A parametric study is performed to determine the effects of the cylinder center distance, inclined angle, static contact angle, and radius on the vertical force. Several key conclusions are derived from the study: (1 Although the lift force increases with the cylinder center distance, cylinders with smaller center distances can penetrate deeper below the water surface before sinking, thereby obtaining a larger maximum lift force; (2 An increase in the inclined angle reduces the lift force, which can enable the lower cylinders fall more deeply before sinking; (3 While the effect of static contact angle is limited for angles greater than 90°, hydrophobicity allows cylinders to obtain a larger lift force and load capacity on water; (4 The lift force increases rapidly with cylinder radius, but an increase in radius also increases the overall size and weight of cylinders and decreases the proportion of the surface tension force. These findings may prove helpful in the design of supporting legs of biologically-inspired miniature aquatic devices, such as water strider robots.

  17. Analyze of aerodynamic forces acting on the Siemens Desiro railcar

    Directory of Open Access Journals (Sweden)

    Sorin ARSENE

    2016-06-01

    Full Text Available This paper aims to examine the influence of aerodynamic forces acting on the Siemens Desiro railcar, and the percentage of these forces in the total values of resistance to motion. In this regard the numerical simulation of the airflow is used as a method of analysis. We started from the 3D geometric model at a scale of 1:1 of the vehicle bodywork constructive form. The air flow simulation is performed taking into account the speed limits of the vehicle namely 0 km/ h and 140 km/ h, interval in which eight point values are chosen.

  18. Forces Acting on Sessile Droplet on Inclined Surfaces

    OpenAIRE

    Annapragada, S. Ravi; Murthy, Jayathi Y.; Garimella, Suresh V.

    2009-01-01

    Although many analytical, experimental and numerical studies have focused on droplet motion, the mechanics of the droplet while still in its static state, and just before motion starts, are not well understood. A study of static droplets would shed light on the threshold voltage (or critical inclination) for initiating electrically (or gravitationally) induced droplet motion. Before the droplet starts to move, the droplet shape changes such that the forces acting at the triple contact line ba...

  19. Evidence for external forcing temporal clustering of great earthquakes

    Science.gov (United States)

    Khachikyan, Galina; Zhumabayev, Beibit; Toyshiev, Nursultan; Kairatkyzy, Dina; Kaldybayev, Azamat; Nurakynov, Serik

    2016-04-01

    It is shown by Bufe and Perkins [2005, BSSA, doi:10.1785/0120040110] and Shearera and Stark [2012, PNAS, doi: 10.1073/pnas.1118525109] that clustering of great earthquakes in 1950-1965 and 2004-2011 years is highly significant, with a 0.5% probability of random occurrence. Lutikov and Rogozhin [2014, Physics of the Solid Earth] reported on a similar clustering in the end of 19th - beginning of 20ty centuries as well, when strongest earthquakes occurred in Tien Shan (1889, M=8.3; and 1911, M=8.2); Alaska (1899, M=8.0); Kashgaria (1902, M=8.2); Mongolia (1905, M=8.2); San Francisco (1906, M=8.3), China(1906, M=8.3); Columbia (1906, M=8.6). Shearera and Stark [2012] have found that clustering of great earthquakes is analogous to seismic swarms that occur for a limited time. Simultaneously, they mentioned that at present no physical mechanism has been proposed to explain possible global seismicity swarms. Our results suggest that a mechanism responsible for temporal clustering of great earthquakes could be an external one related to the processes in the whole solar system including the Sun. We pay attention that the three marked periods of great earthquake clustering are related closely to the extreme phases of the recent Solar Centennial Gleissberg Cycle, which minimums occurred around of 1913 and 2008 years, and maximum - around of 1960 year. In particular, the great earthquake clustering in 1950-1965 coincides closely with the extremely high 19th eleven year solar cycle lasting from February 1954 to October 1964, while a great earthquake clustering after 2004 year coincides closely with the recent prolonged solar minimum developing after 2000 year. Also, we demonstrate that depending on the structure and composition of the lithosphere, strongest earthquakes may prefer to occur either in high or low solar activity. In particular, data analysis for 32 strongest (M=>7.0) earthquakes occurred in 1973-2014 years in the orogeny region of Eurasia, restricted by coordinates

  20. Impacts of external forcing on the 20th century global warming

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The impacts of external forcing, including natural and anthropogenic, on the 20th century global warming were assessed with the use of the Grid Atmospheric Model of IAP/LASG Version 1.1.0, following the standard coordinated experiment design of the Climate Variability and Predictability (CLIVAR) International Climate of the Twentieth Century Project (C20C), Phase II. The results indicate that external forcing plays an important role in the evolution of the land surface air temperature on interannual, decadal, and interdecadal time scales, and contributes greatly to the global warming in the following two periods: the early twentieth century between the 1910s and the 1940s and the late twentieth century after the 1970s. External forcing also has strong impact on the regional temperature change during the two warming periods except for parts of the Eurasia and the North America continents. In the cooling period, however, the impact of internal variability is dominant.

  1. Malaria Vaccine Development and How External Forces Shape It: An Overview

    OpenAIRE

    Veronique Lorenz; Gabriele Karanis; Panagiotis Karanis

    2014-01-01

    The aim of this paper is to analyse the current status and scientific value of malaria vaccine approaches and to provide a realistic prognosis for future developments. We systematically review previous approaches to malaria vaccination, address how vaccine efforts have developed, how this issue may be fixed, and how external forces shape vaccine development. Our analysis provides significant information on the various aspects and on the external factors that shape malaria vaccine development...

  2. An active optimal control strategy of rotor vibrations using external forces

    Science.gov (United States)

    Zhu, W.; Castelazo, I.; Nelson, H. D.

    1989-01-01

    An active control strategy for lateral rotor vibrations using external forces is proposed. An extended state observer is used to reconstruct the full states and the unbalance distribution. An optimal controller which accommodates persistent unbalance excitation is derived with feedback of estimated states and unbalances. Numerical simulations were conducted for two separate four degree of freedom rotor systems. These simulations indicated that the proposed strategy can achieve almost complete vibration cancellation. This was shown to be true even when the number of external control forces was less than the system order so long as coordinate coupling was present. Both steady state and transient response at a constant speed are presented.

  3. Pull-in control due to Casimir forces using external magnetic fields

    CERN Document Server

    Esquivel-Sirvent, R; Cocoletzi, G H

    2009-01-01

    We present a theoretical calculation of the pull-in control in capacitive micro switches actuated by Casimir forces, using external magnetic fields. The external magnetic fields induces an optical anisotropy due to the excitation of magneto plasmons, that reduces the Casimir force. The calculations are performed in the Voigt configuration, and the results show that as the magnetic field increases the system becomes more stable. The detachment length for a cantilever is also calculated for a cantilever, showing that it increases with increasing magnetic field. At the pull-in separation, the stiffness of the system decreases with increasing magnetic field.

  4. Analysis of the forces acting on beating cilia

    Science.gov (United States)

    Sangani, Ashok S.; Vidyadharan, Jyothish; Foster, Kenneth W.

    2016-06-01

    Detailed analysis of the forces acting on a uniform-diameter beating cilium is carried out to determine the moment generated by the inter-doublet forces acting along the length of a cilium and the results are compared with the sliding-control theory according to which the moment is a function of the interdoublet sliding. In the central part of the cilium the inter-doublet forces are found to be proportional to the inter-doublet sliding. However, in spite of the uniformity of the diameter of the cilium, the proportionality constant, known as the dynamic stiffness, is not constant along its entire length. Significant variations are observed in the regions both near the tip of the cilium and proximal to the cell body. In the tip region the magnitude of the dynamic stiffness is found to decrease. This decrease is probably due to decrease in the number density of the molecular motors in that region and in the number of doublet microtubules. The behavior in the proximal region, on the other hand, does not appear to be well described by the sliding control theory. Our analysis therefore suggests that the dynamics of ciliary beating cannot be adequately described by a simple sliding-control theory with constant dynamic stiffness. Our analysis suggests that the cilium is differentiated into a basal region optimized for the creation of a wave and a central region optimized to support a traveling wave that provides the thrust for the cell.

  5. A study on forces acting on a flapping wing

    OpenAIRE

    Cetiner O.; Fenercioglu I.; Vuruskan A.

    2013-01-01

    In order to study the forces acting on a flapping wing, an experimental investigation is performed in steady water flow. In this study, a SD7003 airfoil undergoes combined pitching and plunging motion which simulates the forward flight of small birds. The frequency of pitching motion is equal to the frequency of plunging motion and pitch leads the plunge by a phase angle of 90 degrees. The experiments are conducted at Reynolds numbers of 2500 ≤ Re ≤ 13700 and the vortex formation is recorded ...

  6. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction.

    Science.gov (United States)

    Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian

    2014-02-21

    The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm.

  7. Symmetries, conservation laws, and time reversibility for Hamiltonian systems with external forces

    NARCIS (Netherlands)

    Schaft, A.J. van der

    1983-01-01

    A system theoretic framework is given for the description of Hamiltonian systems with external forces and partial observations of the state. It is shown how symmetries and conservation laws can be defined within this framework. A generalization of Noether's theorem is obtained. Finally a precise def

  8. A piecewise-integration method for simulating the influence of external forcing on climate

    Institute of Scientific and Technical Information of China (English)

    Zhifu Zhang; Chongjian Qiu; Chenghai Wang

    2008-01-01

    Climate drift occurs in most general circulation models (GCMs) as a result of incomplete physical and numerical representation of the complex climate system,which may cause large uncertainty in sensitivity experiments evaluating climate response to changes in external forcing.To solve this problem,we propose a piecewise-integration method to reduce the systematic error in climate sensitivity studies.The observations are firstly assimilated into a numerical model by using the dynamic relaxation technique to relax to the current state of atmosphere,and then the assimilated fields are continuously used to reinitialize the simulation to reduce the error of climate simulation.When the numerical model is integrated with changed external forcing,the results can be split into two parts,background and perturbation fields,and the background is the state before the external forcing is changed.The piecewise-integration method is used to continuously reinitialize the model with the assimilated field,instead of the background.Therefore,the simulation error of the model with the external forcing can be reduced.In this way,the accuracy of climate sensitivity experiments is greatly improved.Tests with a simple low-order spectral model show that this approach can significantly reduce the uncertainty of climate sensitivity experiments.

  9. Materials Bound by Non-Chemical Forces: External Fields and the Quantum Vacuum

    CERN Document Server

    Swain, John; Srivastava, Yogendra

    2014-01-01

    We discuss materials which owe their stability to external fields. These include: 1) external electric or magnetic fields, and 2) quantum vacuum fluctuations in these fields induced by suitable boundary conditions (the Casimir effect). Instances of the first case include the floating water bridge and ferrofluids in magnetic fields. An example of the second case is taken from biology where the Casimir effect provides an explanation of the formation of stacked aggregations or "rouleaux" by negatively charged red blood cells. We show how the interplay between electrical and Casimir forces can be used to drive self-assembly of nano-structured materials, and could be generalized both as a probe of Casimir forces and as a means of manufacturing nanoscale structures. Interestingly, all the cases discussed involve the generation of the somewhat exotic negative pressures. We note that very little is known about the phase diagrams of most materials in the presence of external fields other than those represented by the ...

  10. Fingerprints in the clouds: identifying expected cloud responses to external forcing

    Science.gov (United States)

    Marvel, K.; Zelinka, M. D.

    2013-12-01

    Changes in cloud properties in response to external forcing affect the radiation budget of the Earth, which in turn affects the equilibrium climate response. Reconciling modeled and observed cloud trends is therefore crucial in understanding climate sensitivity and the response to anthropogenic increases in greenhouse gas concentrations. While cloud responses differ greatly across models, errors in the locations of large-scale features can obscure even those physical processes that are robust across multiple models. We propose a method to track changes in cloud height, amount, and vertical profile across multiple models, and show that certain characteristics of the response are present in most models. This allows us to calculate a multidimensional fingerprint representing the characteristic cloud response to external forcing. We show how this fingerprint changes when various relevant forcing terms are included or excluded, and differentiate between models with high and low climate sensitivities. This represents an important first step toward detection and attribution of cloud trends.

  11. External forces influence the elastic coupling effects during cargo transport by molecular motors.

    Science.gov (United States)

    Berger, Florian; Keller, Corina; Klumpp, Stefan; Lipowsky, Reinhard

    2015-02-01

    Cellular transport is achieved by the cooperative action of molecular motors which are elastically linked to a common cargo. When the motors pull on the cargo at the same time, they experience fluctuating elastic strain forces induced by the stepping of the other motors. These elastic coupling forces can influence the motors' stepping and unbinding behavior and thereby the ability to transport cargos. Based on a generic single motor description, we introduce a framework that explains the response of two identical molecular motors to a constant external force. In particular, we relate the single motor parameters, the coupling strength and the external load force to the dynamics of the motor pair. We derive four distinct transport regimes and determine how the crossover lines between the regimes depend on the load force. Our description of the overall cargo dynamics takes into account relaxational displacements of the cargo caused by the unbinding of one motor. For large forces and weak elastic coupling these back-shifts dominate the displacements. To develop an intuitive understanding about motor cooperativity during cargo transport, we introduce a time scale for load sharing. This time scale allows us to predict how the regulation of single motor parameters influences the cooperativity. As an example, we show that up-regulating the single motor processivity enhances load sharing of the motor pair.

  12. Active contour external force using vector field convolution for image segmentation.

    Science.gov (United States)

    Li, Bing; Acton, Scott T

    2007-08-01

    Snakes, or active contours, have been widely used in image processing applications. Typical roadblocks to consistent performance include limited capture range, noise sensitivity, and poor convergence to concavities. This paper proposes a new external force for active contours, called vector field convolution (VFC), to address these problems. VFC is calculated by convolving the edge map generated from the image with the user-defined vector field kernel. We propose two structures for the magnitude function of the vector field kernel, and we provide an analytical method to estimate the parameter of the magnitude function. Mixed VFC is introduced to alleviate the possible leakage problem caused by choosing inappropriate parameters. We also demonstrate that the standard external force and the gradient vector flow (GVF) external force are special cases of VFC in certain scenarios. Examples and comparisons with GVF are presented in this paper to show the advantages of this innovation, including superior noise robustness, reduced computational cost, and the flexibility of tailoring the force field.

  13. Numerical Method for Wave Forces Acting on Partially Perforated Caisson

    Institute of Scientific and Technical Information of China (English)

    姜峰; 唐晓成; 金钊; 张莉; 陈洪洲

    2015-01-01

    The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid–structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier–Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.

  14. Numerical method for wave forces acting on partially perforated caisson

    Science.gov (United States)

    Jiang, Feng; Tang, Xiao-cheng; Jin, Zhao; Zhang, Li; Chen, Hong-zhou

    2015-04-01

    The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid-structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier-Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.

  15. Pipeline integrity management: integration of geotechnical and mechanical assessment to control potential risks due to external forces

    Energy Technology Data Exchange (ETDEWEB)

    Malpartida Moya, John E.; Sota, Giancarlo Massucco de la; Seri, Walter [Compania Operadora de Gas del Amazonas, Lima (Peru)

    2009-07-01

    Every pipeline integrity management system evaluates and controls various threats. On pipelines which have particular characteristics as it is the case of the Andean pipelines and pipelines crossing jungles, one of the main threats are the external forces. Even, this threat causes a greater number of failures than other threats like corrosion or the third part damage. Facing this situation, the pipeline integrity management system of TgP has achieved an important development in the use and suitable handling of the information provided by diverse techniques of pipeline mechanical inspection and geotechnical inspection of the right-of-way (ROW). This document presents our methodology, which interrelate information of the in-line inspection, information of geotechnical inspections of the ROW, instrumentation (Strain Gages), topographic monitoring, among others. All this information is supported in a Geographic Information System (GIS) which allows us to integrate the information. By means of the pipeline integrity management system we control potential risks due to external forces, we have been able to act before events become critical, with no occurrence of failures. This system allows us simultaneously to optimize efforts and preserve the mechanical integrity of our pipelines, not producing neither personal nor environmental nor economical affectation. (author)

  16. Enhanced Diffusion of Molecular Motors in the Presence of Adenosine Triphosphate and External Force

    Science.gov (United States)

    Shinagawa, Ryota; Sasaki, Kazuo

    2016-06-01

    The diffusion of a molecular motor in the presence of a constant external force is considered on the basis of a simple theoretical model. The motor is represented by a Brownian particle moving in a series of parabolic potentials placed periodically on a line, and the potential is switched stochastically from one parabola to another by a chemical reaction, which corresponds to the hydrolysis or synthesis of adenosine triphosphate (ATP) in motor proteins. It is found that the diffusion coefficient as a function of the force exhibits peaks. The mechanism of this diffusion enhancement and the possibility of observing it in F1-ATPase, a biological rotary motor, are discussed.

  17. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models

    Science.gov (United States)

    Alvarez-Nodarse, R.; Quintero, N. R.; Mertens, F. G.

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  18. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models.

    Science.gov (United States)

    Alvarez-Nodarse, R; Quintero, N R; Mertens, F G

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  19. External Periodic Force Control of a Single-Degree-of-Freedom Vibroimpact System

    Directory of Open Access Journals (Sweden)

    Jingyue Wang

    2013-01-01

    Full Text Available A single-degree-of-freedom mechanical model of vibro-impact system is established. Bifurcation and chaos in the system are revealed with the time history diagram, phase trajectory map, and Poincaré map. According to the bifurcation and chaos of the actual vibro-impact system, the paper puts forward external periodic force control strategy. The method of controlling chaos by external periodic force feedback controller is developed to guide chaotic motions towards regular motions. The stability of the control system is also analyzed especially by theory. By selecting appropriate feedback coefficients, the unstable periodic orbits of the original chaotic orbit can be stabilized to the stable periodic orbits. The effectiveness of this control method is verified by numerical simulation.

  20. Quantifying internally generated and externally forced climate signals at regional scales in CMIP5 models

    Science.gov (United States)

    Lyu, Kewei; Zhang, Xuebin; Church, John A.; Hu, Jianyu

    2015-11-01

    The Earth's climate evolves because of both internal variability and external forcings. Using Coupled Model Intercomparison Project Phase 5 (CMIP5) models, here we quantify the ratio of externally forced variance to total variance on interannual and longer time scales for regional surface air temperature (SAT) and sea level, which depends on the relative strength of externally forced signal compared to internal variability. The highest ratios are found in tropical areas for SAT but at high latitudes for sea level over the historical period when ocean dynamics and global mean thermosteric contributions are considered. Averaged globally, the ratios over a fixed time interval (e.g., 30 years) are projected to increase during the 21st century under the business-as-usual scenario (RCP8.5). In contrast, under two mitigation scenarios (RCP2.6 and RCP4.5), the ratio declines sharply by the end of the 21st century for SAT, but only declines slightly or stabilizes for sea level, indicating a slower response of sea level to climate mitigation.

  1. Propagation of the state change induced by external forces in local interactions

    Science.gov (United States)

    Lu, Jianjun; Tokinaga, Shozo

    2016-10-01

    This paper analyses the propagation of the state changes of agents that are induced by external forces applied to a plane. In addition, we propose two models for the behavior of the agents placed on a lattice plane, both of which are affected by local interactions. We first assume that agents are allowed to move to another site to maximise their satisfaction. Second, we utilise a model in which the agents choose activities on each site. The results show that the migration (activity) patterns of agents in both models achieve stability without any external forces. However, when we apply an impulsive external force to the state of the agents, we then observe the propagation of the changes in the agents' states. Using simulation studies, we show the conditions for the propagation of the state changes of the agents. We also show the propagation of the state changes of the agents allocated in scale-free networks and discuss the estimation of the agents' decisions in real state changes. Finally, we discuss the estimation of the agents' decisions in real state temporal changes using economic and social data from Japan and the United States.

  2. Temperature response to external forcing in simulations and reconstructions of the last millennium

    Directory of Open Access Journals (Sweden)

    L. Fernández-Donado

    2012-08-01

    Full Text Available The understanding of natural climate variability and its driving factors is crucial to assess future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleoclimate model simulations is key to gain insights into the relative roles of internal versus forced variability. A review of the state of modeling of the last millennium climate previous to the CMIP5-PMIP3 coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition of the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions, thus advocating for internal variability as a possible major player in shaping temperature changes through the millennium.

    A paleo transient climate response (PTCR is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed PTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change.

  3. Agency elicits body-ownership: proprioceptive drift toward a synchronously acting external proxy.

    Science.gov (United States)

    Asai, Tomohisa

    2016-05-01

    Awareness of our own bodies (sense of body-ownership) and actions (sense of agency) is fundamental for self-consciousness. In the rubber hand illusion, watching a rubber hand being stroked synchronously as one's own unseen hand is also stroked causes the observer to attribute the rubber hand to their own body. The findings of the series of experiments reported here suggest that body-ownership, measured using proprioceptive drift, is elicited by the external acting proxy that drives the sense of agency. While participants clasped and unclasped their left hand for 60 s, they focused on video feedback on a monitor in front of them. Proprioceptive drift was observed only under the conditions, including synchronized conditions, where the sense of agency for the acting proxy occurred, suggesting an essential interaction between body-ownership and agency.

  4. Monsoonal Responses to External Forcings over the Past Millennium: A Model Study (Invited)

    Science.gov (United States)

    Liu, J.; Wang, B.

    2009-12-01

    The climate variations related to Global Monsoon (GM) and East Asian summer monsoon (EASM) rainfall over the past 1000 years were investigated by analysis of a pair of millennium simulations with the coupled climate model named ECHO-G. The free run was generated using fixed external (annual cycle) forcing, while the forced run was obtained using time-varying solar irradiance variability, greenhouse gases (CO2 and CH4) concentration and estimated radiative effect of volcanic aerosols. The model results indicate that the centennial-millennial variation of the GM and EASM is essentially a forced response to the external radiative forcings (insolation, volcanic aerosols, and greenhouse gases). The GM strength responds more directly to the effective solar forcing (insolation plus radiative effect of the volcanoes) when compared to responses of the global mean surface temperature on centennial timescale. The simulated GM precipitation in the forced run exhibits a significant quasi-bi-centennial oscillation. Weak GM precipitation was simulated during the Little Ice Age (1450-1850) with three weakest periods concurring with the Spörer, Maunder, and Dalton Minimum of solar activity. Conversely, strong GM was simulated during the model Medieval Warm Period (ca. 1030-1240). Before the industrial period, the natural variation in effective solar forcing reinforces the thermal contrasts both between the ocean and continent and between the northern and southern hemispheres, resulting in millennium-scale variation and the quasi-bi-centennial oscillation of the GM. The prominent upward trend in the GM precipitation occurring in the last century and the remarkably strengthening of the global monsoon in the period of 1961-1990 appear unprecedented and owed possibly in part to the increase of atmospheric carbon dioxide concentration. The EASM has the largest meridional extent (5oN-55oN) among all the regional monsoons on globe. Thus, the EASM provides an unique opportunity for

  5. Vortical flows in strongly coupled Yukawa liquids under external forcing - A molecular dynamics approach

    Science.gov (United States)

    Ganesh, Rajaraman; Charan, Harish

    2016-07-01

    Understanding vortical flows under external forcing in two dimensional (2D) fluids is a fundamental paradigm for structure formation in driven, dissipative systems. Considering Yukawa liquid as a prototype for strongly correlated or strongly coupled plasmas characterized by coupling strength (Γ, the ratio of average potential to kinetic energy per particle) and screening parameter (κ, ratio of mean inter-particle distance to shielding length), we address two important problems: 1. Onset of Rayleigh Benard convection cell (RBCC) in 2D Yukawa liquids subject to gravity and external temperature gradient 2. Onset of von Karman vortices in 2D Yukawa liquid under external pressure head, using large scale, first principles molecular dynamics simulations. For typical values of (Γ,κ), existence of a critical external temperature difference is demonstrated, beyond which RBCC are seen to set in. Beyond this critical external temperature difference, the strength of the maximum convective flow velocity is shown to exhibit a new, hitherto unsuspected linear relationship with external temperature difference and with a slope independent of (Γ,κ). The time taken for the transients to settle down to a steady state RBCC τ_s, is found to be maximum close to the above said critical external temperature difference and is seen to reduce with increasing external temperature difference. For the range of values of (Γ, κ) considered here, τ_s ≃ 10 000-20 000;ω^{-1}_{pd}, where ω_{pd} is dust plasma frequency. As Γ is increased to very high values, due to strong coupling effects, RBC cells are seen to be in a transient state without attaining a steady state for as long as 100 000;ω^{-1}_{pd}, even for a very high external temperature difference. In the second part, we address the existence of universal relation between Strouhal (St) and Rayleigh (Ry) numbers for Yukawa liquid using first principles based classical molecular dynamics. The flow past an obstacle is seen to indeed

  6. Streamwise-body-force-model for rapid simulation combining internal and external flow fields

    Directory of Open Access Journals (Sweden)

    Cui Rong

    2016-10-01

    Full Text Available A streamwise-body-force-model (SBFM is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The validation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.

  7. Novel bursting patterns in a Van der pol-Duffing oscillator with slow varying external force

    Science.gov (United States)

    Yu, Yue; Zhao, Min; Zhang, Zhengdi

    2017-09-01

    In this paper, we investigate the emergence of bursting dynamics with complex waveforms and their relation to periodic behavior in typical Van der pol-Duffing equation with fifth order polynomial stiffness nonlinearity, when the external force changes slowly with the variation of time. We exploit bifurcation characteristics of the fast subsystem using the slowly changing periodic excitation as a bifurcation parameter to show how the bursting oscillations are created in this model. We also identify that some regimes of bursting patterns are related to codimension two bifurcation type over a wide range of parameters. A subsequent two-parameter continuation reveals a transition in the bursting behavior from fold/fold hysteresis cycle to sup-Hopf/sup-Hopf or limit point cycle/sub-Hopf bursting type. Furthermore, the effects of external forcing item on bursting oscillations are investigated. For instance, the time interval between two adjacent spikes of bursting oscillations is dependent on the forcing frequency. Some numerical simulations are included to illustrate the validity of our study.

  8. Imprint of external climate forcing on coastal upwelling in past and future climate

    Directory of Open Access Journals (Sweden)

    N. Tim

    2015-11-01

    Full Text Available The Eastern Boundary Upwelling Systems are the major coastal upwelling regions. The trade winds are driving these upwelling regimes located in the subtropics at the eastern boundary of the Atlantic and Pacific Ocean. Here we analyse the impact of the external climate forcing, e.g. the greenhouse gas concentration, solar activity and volcano eruptions, on these upwelling systems in simulations of ensembles of two Earth System Models. The ensembles contain three simulations for each time period which cover the past millennium (900–1850, the 20th century (1850–2005 and the near future (2006–2100. Using a set of simulations, differing only in their initial conditions, enables us to detect whether the variability is driven internally or externally. Our analysis shows that the variability of the simulated upwelling is to the most driven internally and that there are no significant trends except for the scenario with the most dramatic increase of greenhouse gas concentrations.

  9. A Digital Map From External Forcing to the Final Surface Warming Pattern and its Seasonal Cycle

    Science.gov (United States)

    Cai, M.

    2015-12-01

    Historically, only the thermodynamic processes (e.g., water vapor, cloud, surface albedo, and atmospheric lapse rate) that directly influence the top of the atmosphere (TOA) radiative energy flux balance are considered in climate feedback analysis. One of my recent research areas is to develop a new framework for climate feedback analysis that explicitly takes into consideration not only the thermodynamic processes that the directly influence the TOA radiative energy flux balance but also the local dynamical (e.g., evaporation, surface sensible heat flux, vertical convections etc) and non-local dynamical (large-scale horizontal energy transport) processes in aiming to explain the warming asymmetry between high and low latitudes, between ocean and land, and between the surface and atmosphere. In the last 5-6 years, we have developed a coupled atmosphere-surface climate feedback-response analysis method (CFRAM) as a new framework for estimating climate feedback and sensitivity in coupled general circulation models with a full physical parameterization package. In the CFRAM, the isolation of partial temperature changes due to an external forcing alone or an individual feedback is achieved by solving the linearized infrared radiation transfer model subject to individual energy flux perturbations (external or due to feedbacks). The partial temperature changes are addable and their sum is equal to the (total) temperature change (in the linear sense). The CFRAM is used to isolate the partial temperature changes due to the external forcing, due to water vapor feedback, clouds, surface albedo, local vertical convection, and non-local atmospheric dynamical feedbacks, as well as oceanic heat storage. It has been shown that seasonal variations in the cloud feedback, surface albedo feedback, and ocean heat storage/dynamics feedback, directly caused by the strong annual cycle of insolation, contribute primarily to the large seasonal variation of polar warming. Furthermore, the

  10. EXTERNAL FORCES DRIVING CHANGE IN THE ROMANIAN SMALL AND MEDIUM SIZED ENTERPRISES

    Directory of Open Access Journals (Sweden)

    Roiban Roxana Nadina

    2012-07-01

    Full Text Available Change is a constant in everyday life confronting organizations to continuously adapt their strategy, structure, processes, and culture in order to survive and stay competitive on the market. Implementing organizational change is one of the most important skills required for managers and in the meantime the most difficult one. The forces driving change within an organization, that can be either external or internal, are those that propel a company forward towards change and in order to identify the need for change and make the proper changes, managers have to develop a tool that allows them to analyze how does the environment influence their business activities. A vision for change will clarify the directions in which the organization needs to move, starting from its current state and taking in consideration the existing opportunities and threats from the environment that allow to move to a future desired state. The purpose of this paper is to identify the concern for change in the Romanian small and medium sized enterprises by presenting and explaining the past and present influences of the main external forces that have determined the need for change in the last 3-5 years and to make recommendations about future possible changes that have to be performed by managers for a better harmonization with the environment. The research method used for this study is the interview on a sample that contains some of the most relevant SME’s from the western side of Romania, from different industries. We analyzed the main external forces that had an impact on the small and medium sized enterprises and how were they generating the need for organizational change, in order to see which present and future changes are required.

  11. A Stability Criterion for Time-Delay Tension Leg Platform Systems Subjected to External Force

    Institute of Scientific and Technical Information of China (English)

    Chen-Yuan CHEN; Chien-wen SHEN; Cheng-Wu CHEN; Kevin Fong-Rey LIU; Ming-Jen CHENG

    2009-01-01

    Stability analysis plays a central role in nonlinear system theory and engineering application.Over the past few yeats,the stability analysis of fuzzy systems has been proposed and there are many successful applications in practical engineering.Therefore,in this paper firstly proposed is the stability analysis on oceanic structure by fuzzy models.In the present study,Takagi-Sugeno (T-S) fuzzy model is proposed for a time delay tension leg platform (TLP) system subjected to an external wave force.In terms of stability analysis,linear matrix inequality (LMI) conditions are derived via Lyapunov theory to guarantee the stability of the TLP system.

  12. Estimation of Coriolis Force and Torque Acting on Ares-1

    Science.gov (United States)

    Mackey, Ryan M.; Kulikov, Igor K.; Smelyanskiy, Vadim; Luchinsky, Dmitry; Orr, Jeb

    2011-01-01

    A document describes work on the origin of Coriolis force and estimating Coriolis force and torque applied to the Ares-1 vehicle during its ascent, based on an internal ballistics model for a multi-segmented solid rocket booster (SRB).

  13. A simple method to construct soliton-like solution of the general KdV equation with external force

    Institute of Scientific and Technical Information of China (English)

    JiefangZHANG; FengminWU

    2000-01-01

    A simple and direct method is described to construct the soliton-like solution for the general KdV equation with external force. Crucial to the method is the assumption that the solution chosen is a special truncated expansion.

  14. Study of deformation of droplet in external force field by using liquid-gas model of lattice-gas

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Ken-ichi; Watanabe, Tadashi [Japan Atomic Energy Research Inst., Center for Promotion of Computational Science and Engineering, Tokai, Ibaraki (Japan)

    2000-10-01

    The deformation of the droplet by the external force which is assumed to be gravity is studied by using the liquid-gas model of lattice-gas. Two types of liquid-gas models, one is the minimal model and the other is the maximal model, which are distinguished from each other by the added long-range interactions are used for the simulation of the droplet deformation. The difference of the droplet deformation between the maximal model and the minimal model was observed. While the droplet of the minimal model elongates in the direction of the external force, the droplet of the maximal model elongates in the perpendicular direction to the external force. Therefore the droplet deformation in the external force field of the maximal model is more similar to the droplet deformation which is observed in experiments than that of the minimal model. (author)

  15. Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal

    CERN Document Server

    Gallet, Basile; Mordant, Nicolas

    2009-01-01

    We report an experimental investigation on the influence of an external magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We observe an exponential damping of the turbulent velocity fluctuations as a function of the interaction parameter N (ratio of Lorentz force over inertial terms of the Navier-Stokes equation). The flow structures develop some anisotropy but do not become bidimensional. From a dynamical viewpoint, the damping first occurs homogeneously over the whole spectrum of frequencies. For larger values of N, a very strong additional damping occurs at the highest frequencies. However, the injected mechanical power remains independent of the applied magnetic field. The simultaneous measurement of induced magnetic field and electrical potential differences shows a very weak correlation between magnetic field and velocity fluctuations. The observed reduction of the fluctuations is in agreement with a previously proposed mechanism for the saturation of turbulent dynamos and wit...

  16. Analysis of Externality of Rural Labor Force Flow in Central and Western Regions of China and Benefit Compensation

    Institute of Scientific and Technical Information of China (English)

    Xin; LI; Haijing; HU

    2013-01-01

    According to the theories of institutional economics and development economics,the positive and negative externality of rural labor force flowing from central and western regions and into eastern regions of China were analyzed,and then it was proposed that it is necessary to positive externality,rather than take"household register"measures to solve the problem simply.

  17. Bidirectional transport by molecular motors: enhanced processivity and response to external forces.

    Science.gov (United States)

    Müller, Melanie J I; Klumpp, Stefan; Lipowsky, Reinhard

    2010-06-02

    Intracellular transport along cytoskeletal filaments is often mediated by two teams of molecular motors that pull on the same cargo and move in opposite directions along the filaments. We have recently shown theoretically that this bidirectional transport can be understood as a stochastic tug-of-war between the two motor teams. Here, we further develop our theory to investigate the experimentally accessible dynamic behavior of cargos transported by strong motors such as kinesin-1 or cytoplasmic dynein. By studying the run and binding times of such a cargo, we show that the properties of biological motors, such as the large ratio of stall/detachment force and the small ratio of superstall backward/forward velocity, are favorable for bidirectional cargo transport, leading to fast motion and enhanced diffusion. In addition, cargo processivity is shown to be strongly enhanced by transport via several molecular motors even if these motors are engaged in a tug-of-war. Finally, we study the motility of a bidirectional cargo under force. Frictional forces arising, e.g., from the viscous cytoplasm, lead to peaks in the velocity distribution, while external forces as exerted, e.g., by an optical trap, lead to hysteresis effects. Our results, in particular our explicit expressions for the cargo binding time and the distance of the peaks in the velocity relation under friction, are directly accessible to in vitro as well as in vivo experiments.

  18. External Load Affects Ground Reaction Force Parameters Non-uniformly during Running in Weightlessness

    Science.gov (United States)

    DeWitt, John; Schaffner, Grant; Laughlin, Mitzi; Loehr, James; Hagan, R. Donald

    2004-01-01

    Long-term exposure to microgravity induces detrimefits to the musculcskdetal system (Schneider et al., 1995; LeBlanc et al., 2000). Treadmill exercise is used onboard the International Space Station as an exercise countermeasure to musculoskeletal deconditioning due to spaceflight. During locomotive exercise in weightlessness (0G), crewmembers wear a harness attached to an external loading mechanism (EL). The EL pulls the crewmember toward the treadmill, and provides resistive load during the impact and propulsive phases of gait. The resulting forces may be important in stimulating bone maintenance (Turner, 1998). The EL can be applied via a bungee and carabineer clip configuration attached to the harness and can be manipulated to create varying amounts of load levels during exercise. Ground-based research performed using a vertically mounted treadmill found that peak ground reaction forces (GRF) during running at an EL of less than one body weight (BW) are less than those that occur during running in normal gravity (1G) (Davis et al., 1996). However, it is not known how the GRF are affected by the EL in a true OG environment. Locomotion while suspended may result in biomechanics that differ from free running. The purpose of this investigation was to determine how EL affects peak impact force, peak propulsive force, loading rate, and impulse of the GRF during running in 0G. It was hypothesized that increasing EL would result in increases in each GRF parameter.

  19. Influence of external forcings on abrupt millennial-scale climate changes: a statistical modelling study

    Science.gov (United States)

    Mitsui, Takahito; Crucifix, Michel

    2016-07-01

    The last glacial period was punctuated by a series of abrupt climate shifts, the so-called Dansgaard-Oeschger (DO) events. The frequency of DO events varied in time, supposedly because of changes in background climate conditions. Here, the influence of external forcings on DO events is investigated with statistical modelling. We assume two types of simple stochastic dynamical systems models (double-well potential-type and oscillator-type), forced by the northern hemisphere summer insolation change and/or the global ice volume change. The model parameters are estimated by using the maximum likelihood method with the NGRIP Ca^{2+} record. The stochastic oscillator model with at least the ice volume forcing reproduces well the sample autocorrelation function of the record and the frequency changes of warming transitions in the last glacial period across MISs 2, 3, and 4. The model performance is improved with the additional insolation forcing. The BIC scores also suggest that the ice volume forcing is relatively more important than the insolation forcing, though the strength of evidence depends on the model assumption. Finally, we simulate the average number of warming transitions in the past four glacial periods, assuming the model can be extended beyond the last glacial, and compare the result with an Iberian margin sea-surface temperature (SST) record (Martrat et al. in Science 317(5837): 502-507, 2007). The simulation result supports the previous observation that abrupt millennial-scale climate changes in the penultimate glacial (MIS 6) are less frequent than in the last glacial (MISs 2-4). On the other hand, it suggests that the number of abrupt millennial-scale climate changes in older glacial periods (MISs 6, 8, and 10) might be larger than inferred from the SST record.

  20. Global Forces in Eruptive Solar Flares: The Lorentz Force Acting on the Solar Atmosphere and the Solar Interior

    Science.gov (United States)

    Fisher, George H.; Bercik, D. J.; Welsch, B. T.; Hudson, H. S.

    2012-05-01

    We compute the change in the Lorentz force integrated over the outer solar atmosphere implied by observed changes in vector magnetograms that occur during large, eruptive solar flares. This force perturbation should be balanced by an equal and opposite force perturbation acting on the solar photosphere and solar interior. The resulting expression for the estimated force change in the solar interior generalizes the earlier expression presented by Hudson, Fisher, and Welsch, providing horizontal as well as vertical force components, and provides a more accurate result for the vertical component of the perturbed force. We show that magnetic eruptions should result in the magnetic field at the photosphere becoming more horizontal, and hence should result in a downward (toward the solar interior) force change acting on the photosphere and solar interior, as recently argued from an analysis of magnetogram data by Wang and Liu. We suggest the existence of an observational relationship between the force change computed from changes in the vector magnetograms, the outward momentum carried by the ejecta from the flare, and the properties of the helioseismic disturbance driven by the downward force change. We use the impulse driven by the Lorentz-force change in the outer solar atmosphere to derive an upper limit to the mass of erupting plasma that can escape from the Sun. Finally, we compare the expected Lorentz-force change at the photosphere with simple estimates from flare-driven gasdynamic disturbances and from an estimate of the perturbed pressure from radiative backwarming of the photosphere in flaring conditions.

  1. Influence of AC external magnetic field on guidance force relaxation between HTS bulk and NdFeB guideway

    Science.gov (United States)

    Zhang, Longcai; Wang, Suyu; Wang, Jiasu; Zheng, Jun

    2007-12-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.

  2. Is climate change an unforeseen, irresistible and external factor - A force majeure in marine environmental law?

    Science.gov (United States)

    Saul, Roxanne; Barnes, Richard; Elliott, Michael

    2016-12-15

    Several environmental laws include provisions on natural causes or force majeure, which except States from their commitments if it can be proven that the failure to meet the commitment is due to factors outside their control. The European Union Marine Strategy Framework Directive (MSFD) has a pivotal role in managing EU marine waters. This paper analyses natural causes and force majeure provisions of the MFSD and other marine legislation, and addresses their interaction with climate change and its consequences, especially the effect on the obligation of ensuring seas are in Good Environmental Status. Climate change is an exogenic unmanaged pressure in that it emanates from outside the area being managed but in which the management authority has to respond to the consequences of climate change, such as sea level rise and temperature elevation, rather than its causes. It is suggested that a defence by a Member State of force majeure may be accepted if an event was proven to be due to an externality of control, irresistible and unforeseeable. The analysis contends that countering such a legal defence would centre on the fact that climate change is a well-accepted phenomenon, is foreseen with an accepted level of confidence and probability and is due to human actions. However, as yet, this has not been legally tested.

  3. Drag force acting on a neuromast in the fish lateral line trunk canal. II. Analytical modelling of parameter dependencies.

    Science.gov (United States)

    Humphrey, Joseph A C

    2009-07-01

    In Part I of this two-part study, the coupled flows external and internal to the fish lateral line trunk canal were consecutively calculated by solving the Navier-Stokes (N-S) equations numerically in each domain. With the external flow known, the solution for the internal flow was obtained using a parallelepiped to simulate the neuromast cupula present between a pair of consecutive pores, allowing the calculation of the drag force acting on the neuromast cupula. While physically rigorous and accurate, the numerical approach is tedious and inefficient since it does not readily reveal the parameter dependencies of the drag force. In Part II of this work we present an analytically based physical-mathematical model for rapidly calculating the drag force acting on a neuromast cupula. The cupula is well approximated as an immobile sphere located inside a tube-shaped canal segment of circular cross section containing a constant property fluid in a steady-periodic oscillating state of motion. The analytical expression derived for the dimensionless drag force is of the form |F(N)/(|P(L) - P(R)|pi(D/2)(2) = f(d/D, L(t)/D, omega(*)(D), where |F(N)| is the amplitude of the drag force; |P(L)-P(R)| is the amplitude of the pressure difference driving the flow in the interpore tube segment; d/D is the ratio of sphere diameter to tube diameter; L(t)/D is the ratio of interpore tube segment length to tube diameter; and omega(*)(D) = omega(D/2)(2) /v is the oscillating flow kinetic Reynolds number (a dimensionless frequency). Present results show that the dimensionless drag force amplitude increases with decreasing L(t)/D and maximizes in the range 0.65< or =d/D< or =0.85, depending on the values of L(t)/D and omega(*)(D). It is also found that in the biologically relevant range of dimensionless frequencies 1< or = omega(*)(D) < or =20 and segment lengths 4< or =L(t)/D< or =16, the sphere tube (neuromast-canal) system acts as a low-pass filter for values d/D< or =0.75, approximately

  4. A district nurse's guide to the Forced Marriage (Civil Protection) Act 2007.

    Science.gov (United States)

    Griffith, Richard; Tengnah, Cassam

    2009-01-01

    The government considers forced marriage to be a form of domestic abuse with some 3000 cases reported to the forced marriage unit each year in the UK. Both the Home Office and the Foreign and commonwealth office consider health professionals, such as district nurses, to be ideally placed to identify, help and support the victims of forced marriage. To do this effectively district nurses must be aware of the provisions of the Forced Marriage (Civil Protection) Act 2007.

  5. The roles of external forcing and natural variability in global warming hiatuses

    Science.gov (United States)

    Zhang, Lei

    2016-11-01

    Global mean surface temperature (GMST) rising has slowed down since late 1990s, which is referred to as the global warming hiatus. There was another global warming hiatus event during 1940s-1960s. The roles of the external forcing and the natural variability in both global warming hiatuses are explored, using EOF analysis. The first two leading EOF modes of the 5-year running mean global sea surface temperature (SST) reflect the global warming scenario (EOF1) and the interdecadal Pacific oscillation (IPO)-like natural variability (EOF2), respectively. In observation, PC2 was in its positive phase (eastern Pacific cooling) during 1940s-1960s, which contributed to the previous warming hiatus. In addition, GMST trends are found to be negative during late 1950s and 1960s in most of the CMIP5 historical runs, which implies that the external forcing also contributed to the pause in the GMST rising. It is further demonstrated that it is the natural radiative forcing (volcanic forcing) that caused the drop-down of GMST in 1960s. The current global warming hiatus has been attributed to the eastern Pacific cooling/enhanced Pacific trade winds. It is shown that the PC2 switched to its positive phase in late 1990s, and hence the IPO-like natural variability made a contribution to the slowdown of GMST rising in the past decade. It is also found that the EOF1 mode (global warming mode) of the observed SST features a smaller warming in tropical Pacific compared to the Indian Ocean and the tropical Atlantic. Such inter-basin warming contrast, which is attributed to the "ocean thermostat" mechanism, has been suggested to contribute to the intensification of Pacific trade winds since late 1990s as well. Global warming hiatuses are also found in the future projections from CMIP5 models, and the spatial pattern of the SST trends during the warming-hiatus periods exhibits an IPO-like pattern, which resembles the observed SST trends since late 1990s.

  6. Convergence Rate to Stationary Solutions for Boltzmann Equation with External Force

    Institute of Scientific and Technical Information of China (English)

    Seiji UKAI; Tong YANG; Huijiang ZHAO

    2006-01-01

    For the Boltzmann equation with an external force in the form of the gradient of a potential function in space variable, the stability of its stationary solutions as local Maxwellians was studied by S. Ukai et al. (2005) through the energy method. Based on this stability analysis and some techniques on analyzing the convergence rates to stationary solutions for the compressible Navier-Stokes equations, in this paper, we study the convergence rate to the above stationary solutions for the Boltzmann equation which is a fundamental equation in statistical physics for non-equilibrium rarefied gas. By combining the dissipation from the viscosity and heat conductivity on the fluid components and the dissipation on the non-fluid component through the celebrated H-theorem, a convergence rate of the same order as the one for the compressible Navier-Stokes is obtained by constructing some energy functionals.

  7. Solutions to Master equations of quantum Brownian motion in a general environment with external force

    Energy Technology Data Exchange (ETDEWEB)

    Roura, Albert [Los Alamos National Laboratory; Fleming, C H [UNIV OF MARYLAND; Hu, B L [UNIV OF MARYLAND

    2008-01-01

    We revisit the model of a system made up of a Brownian quantum oscillator linearly coupled to an environment made up of many quantum oscillators at finite temperature. We show that the HPZ master equation for the reduced density matrix derived earlier [B.L. Hu, J.P. Paz, Y. Zhang, Phys. Rev. D 45, 2843 (1992)] has incorrectly specified coefficients for the case of nonlocal dissipation. We rederive the QBM master equation, correctly specifying all coefficients, and determine the position uncertainty to be free of excessive cutoff sensitivity. Our coefficients and solutions are reduced entirely to contour integration for analytic spectra at arbitrary temperature, coupling strength, and cut-off. As an illustration we calculate the master equation coefficients and solve the master equation for ohmic coupling (with finite cutoff) and example supra-ohmic and sub-ohmic spectral densities. We determine the effect of an external force on the quantum oscillator and also show that our representation of the master equation and solutions naturally extends to a system of multiple oscillators bilinearly coupled to themselves and the bath in arbitrary fashion. This produces a formula for investigating the standard quantum limit which is central to addressing many theoretical issues in macroscopic quantum phenomena and experimental concerns related to low temperature precision measurements. We find that in a dissipative environment, all initial states settle down to a Gaussian density matrix whose covariance is determined by the thermal reservoir and whose mean is determined by the external force. We specify the thermal covariance for the spectral densities we explore.

  8. The temporal nature of forces acting on metal drops in gas metal arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Jones, L.A.; Eagar, T.W.; Lang, J.H. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1996-12-31

    At moderate and high welding currents, the most important forces in gas metal arc welding acting on the molten electrode are magnetic forces arising from the interaction between the welding current and its own magnetic field. These forces drive the dynamic evolution of the drop and also depend on the instantaneous shape of the drop. In this paper, experimentally observed manifestations of magnetic forces are shown, and a technique for approximating the temporal evolution of these forces from experimentally measured drop shapes is reported. The technique provides quantitative data illustrating the large increase in the magnetic forces as a drop detaches from the electrode.

  9. Experimental evaluation of the drag torque, drag force and Magnus force acting on a rotating prolate spheroid

    OpenAIRE

    Lukerchenko, N. (Nikolay); Keita, I. (Ibrahima); Kvurt, Y.; Miles, J.

    2010-01-01

    The drag torque, drag force and Magnus force acting on a spheroid rotating around its axis of symmetry and moving perpendicularly to this axis in initially quiescent water were studied using experimental data and numerical simulation. The prolate spheroid with ratio of the axes 4/3 was speeded up in special device, which ensured the required rotational and translational velocity in the given plane. A video system was used to record the spheroid motion in water. Using the video records the sph...

  10. Effects of a compression garment on shoulder external rotation force outputs during isotonic contractions.

    Science.gov (United States)

    Tsuruike, Masaaki; Ellenbecker, Todd S

    2013-02-01

    The use of compression garments (CGs) has been advocated for performance enhancement and recovery in athletes. The effect of a CG on humeral rotation motor control has not been previously tested. The purpose of this study was to examine the isotonic contraction of external rotation (ER) of the glenohumeral joint at different force outputs to determine the effect of wearing a long sleeve CG on muscular performance. Twelve male college tennis players and 12 male college soccer players were tested for ER of the dominant shoulder during both concentric and eccentric isotonic contractions. The subjects performed 5 consecutive repetitions of both concentric and eccentric ER at 20-30% and 40-50% of maximum voluntary isometric contraction (MVIC) intensities. All subjects were tested with and without CG as well as with and without ongoing visual feedback information (OVFI). The order of CG wearing and the presence of OVFI were randomly assigned across all subjects. The results indicated a significant 3-way interaction between CG wearing and OVFI across 2 loads. Specifically, significantly different mean value of the completion time was found between OVFI and no-OVFI without CG wearing at 40-50% of MVIC, whereas no difference in the completion time was found with and without OVFI with CG wearing. Taken together, with CG wearing, athletes may have ER at 40-50% of MVIC more readily maintained by peripheral feedback without visuomotor control imposed on force outputs as compared without CG wearing.

  11. A new method to calculate lateral force acting on stabilizing piles based on multi-wedge translation mechanism

    Institute of Scientific and Technical Information of China (English)

    罗渝; 许强; 何思明; 李新坡; 何尽川; 吴永

    2015-01-01

    A new method based on the multi-wedge translation mechanism is presented to calculate the lateral force acting on the stabilizing piles. At first, there is no assumption for the shape of potential sliding surface, it is just considered that the potential sliding surface is a composite of a number of straight lines. And then, the potential sliding mass is divided into a number of triangular wedges take with these straight lines as its base. The kinematic theorem of limit analysis is adopted to calculate the rate of external work and the rate of energy dissipation for each triangular wedge, respectively. Furthermore, the multivariate functions are established to calculate the lateral force acting on the stabilizing piles. The lateral force and the corresponding potential sliding surfaces can be obtained by an optimizational technique. At last, an example is taken to illustrate the method. The effect of soil strength parameters, slope angle and pile roughness on the lateral force and the corresponding potential sliding surface are analyzed. The result are compared with those obtained using other methods.

  12. Acoustic interaction forces and torques acting on suspended spheres in an ideal fluid

    CERN Document Server

    Lopes, J Henrique; Silva, G T

    2014-01-01

    In this paper, the acoustic interaction forces and torques exerted by an arbitrary time-harmonic wave on a set of N spheres suspended in an inviscid fluid are theoretically analyzed. In so doing, we utilize the partial-wave expansion method to solve the related multiple scattering problem. The acoustic interaction force and torque are computed for a sphere using the farfield radiation force and torque formulas. To exemplify the method, we calculate the interaction forces exerted by an external traveling and standing plane wave on an arrangement of two and three olive-oil droplets in water. The droplets radii are comparable to the wavelength (i.e. Mie scattering regime). The results show that the radiation force may considerably deviates from that exerted solely by the external incident wave. In addition, we find that acoustic interaction torques arise on the droplets when a nonsymmetric effective incident wave interacts with the droplets.

  13. Entropic transport without external force in confined channel with oscillatory boundary

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at Microscales, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-12-28

    The dynamics of point-like Brownian particles in a periodic confined channel with oscillating boundaries has been studied. Directional transport (DT) behavior, characterized by net displacement along the horizontal direction, is observed even without external force which is necessary for the conventional DT where the boundaries are static. For typical parameter values, the average velocity V{sub t} of DT reaches a maximum with the variation of the noise intensity D, being alike to the phenomenon of stochastic resonance. Interestingly, we find that V{sub t} shows nontrivial dependences on the particle gravity G depending on the noise level. When the noise is large, V{sub t} increases monotonically with G indicating that heavier particle moves faster, while for small noise, V{sub t} shows a bell-shape dependence on G, suggesting that a particle with an intermediate weight may move the fastest. Such results were not observed for DT in a channel with static boundaries. To understand these findings, we have adopted an effective one-dimensional coarsening description, which facilitates us to introduce an effective entropic force along the horizontal direction. The average force is apparently nonzero due to the oscillatory boundary, hence leading to the net transport, and it shows similar dependences as V{sub t} on the noise intensity D and particle gravity G. The dependences of the DT behavior on other parameters describing the oscillatory channel have also been investigated, showing that DT is more pronounced for larger oscillation amplitude and frequency, and asymmetric geometry within a channel period and phase difference between neighboring periods are both necessary for the occurrence of DT.

  14. External forcing as a source for the observed multi-decadal relation between AMV and the Indian summer monsoon

    Science.gov (United States)

    Svendsen, Lea; Luo, Feifei; Sankar, Syam; Gao, Yongqi; Keenlyside, Noel; Vareed Joseph, Porathur; Johannessen, Ola

    2016-04-01

    The instrumental records show a significant positive correlation between the Atlantic multi-decadal variability (AMV) and the Indian summer monsoon (ISM) rainfall, where a positive (negative) AMV is associated with more (less) ISM rainfall. We have used both proxy reconstruction and twelve models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to investigate if the observed AMV-ISM relation is a persistent internal climate signal or externally forced. A comparison of several annual resolution proxy records both from the Atlantic and for the ISM show that the multi-decadal variability in both indices is persistent, but the link between them is not. The correlation between the two regions is weak, and even negative in some periods, before the instrumental time period. The analysis of CMIP5 simualtions is consistent with these results. While none of the CMIP5 models investigated simulate the significant AMV-ISM connection in the pre-industrial control simulations with fixed external forcing, three of the models reproduce the relation in the 20th century historical simulations with transient forcing. In these models external forcing is linked to the mid-to-upper tropospheric temperature pattern with a strengthened land-ocean contrast over South Asia, consistent with an enhanced ISM, as well as the evolution of AMV. We conclude that the significant AMV-ISM relation found in the observations after the industrial revolution may be associated with external forcing, rather than being internal climate variability.

  15. Unsteady hydrodynamic forces acting on a robotic hand and its flow field.

    Science.gov (United States)

    Takagi, Hideki; Nakashima, Motomu; Ozaki, Takashi; Matsuuchi, Kazuo

    2013-07-26

    This study aims to clarify the mechanism of generating unsteady hydrodynamic forces acting on a hand during swimming in order to directly measure the forces, pressure distribution, and flow field around the hand by using a robotic arm and particle image velocimetry (PIV). The robotic arm consisted of the trunk, shoulder, upper arm, forearm, and hand, and it was independently computer controllable in five degrees of freedom. The elbow-joint angle of the robotic arm was fixed at 90°, and the arm was moved in semicircles around the shoulder joint in a plane perpendicular to the water surface. Two-component PIV was used for flow visualization around the hand. The data of the forces and pressure acting on the hand were sampled at 200Hz and stored on a PC. When the maximum resultant force acting on the hand was observed, a pair of counter-rotating vortices appeared on the dorsal surface of the hand. A vortex attached to the hand increased the flow velocity, which led to decreased surface pressure, increasing the hydrodynamic forces. This phenomenon is known as the unsteady mechanism of force generation. We found that the drag force was 72% greater and the lift force was 4.8 times greater than the values estimated under steady flow conditions. Therefore, it is presumable that swimmers receive the benefits of this unsteady hydrodynamic force.

  16. A statistical modelling study of the abrupt millennial-scale climate changes focusing on the influence of external forcings

    CERN Document Server

    Mitsui, Takahito

    2015-01-01

    Dansgaard-Oeschger (DO) events are abrupt millennial-scale climate changes mainly detected in the North Atlantic region during the last glacial cycle. The frequency of the DO events varied in time, supposedly because of changes in background climate conditions. Here, we investigate the influences of external forcings on DO events with statistical modelling. We assume two types of generic stochastic dynamical systems models (double-well potential-type and oscillator-type), forced by the northern hemisphere summer insolation change and/or the global ice volume change. The models are calibrated by maximizing their likelihood and compared using the Bayesian Information Criterion (BIC). Among the models, the stochastic oscillator model forced by both insolation and ice volume changes is favored by the NGRIP calcium ion data. The BIC scores provide positive evidence for the ice volume forcing in the presence of the insolation forcing but weak evidence for the insolation forcing in the presence of the ice volume for...

  17. Heterogeneous Memorized Continuous Time Random Walks in an External Force Fields

    Science.gov (United States)

    Wang, Jun; Zhou, Ji; Lv, Long-Jin; Qiu, Wei-Yuan; Ren, Fu-Yao

    2014-09-01

    In this paper, we study the anomalous diffusion of a particle in an external force field whose motion is governed by nonrenewal continuous time random walks with correlated memorized waiting times, which involves Reimann-Liouville fractional derivative or Reimann-Liouville fractional integral. We show that the mean squared displacement of the test particle which is dependent on its location of the form (El-Wakil and Zahran, Chaos Solitons Fractals, 12, 1929-1935, 2001) where is the anomalous exponent, the diffusion exponent is dependent on the model parameters. We obtain the Fokker-Planck-type dynamic equations, and their stationary solutions are of the Boltzmann-Gibbs form. These processes obey a generalized Einstein-Stokes-Smoluchowski relation and the second Einstein relation. We observe that the asymptotic behavior of waiting times and subordinations are of stretched Gaussian distributions. We also discuss the time averaged in the case of an harmonic potential, and show that the process exhibits aging and ergodicity breaking.

  18. Acoustic Interaction Forces and Torques Acting on Suspended Spheres in an Ideal Fluid.

    Science.gov (United States)

    Lopes, J Henrique; Azarpeyvand, Mahdi; Silva, Glauber T

    2016-01-01

    In this paper, the acoustic interaction forces and torques exerted by an arbitrary time-harmonic wave on a set of N objects suspended in an inviscid fluid are theoretically analyzed. We utilize the partial-wave expansion method with translational addition theorem and re-expansion of multipole series to solve the related multiple scattering problem. We show that the acoustic interaction force and torque can be obtained using the farfield radiation force and torque formulas. To exemplify the method, we calculate the interaction forces exerted by an external traveling and standing plane wave on an arrangement of two and three olive-oil droplets in water. The droplets' radii are comparable to the wavelength (i.e., Mie scattering regime). The results show that the acoustic interaction forces present an oscillatory spatial distribution which follows the pattern formed by interference between the external and rescattered waves. In addition, acoustic interaction torques arise on the absorbing droplets whenever a nonsymmetric wavefront is formed by the external and rescattered waves' interference.

  19. Biopolymers under large external forces and mean-field RNA virus evolutionary dynamics

    Science.gov (United States)

    Ahsan, Syed Amir

    The modeling of the mechanical response of single-molecules of DNA and RNA under large external forces through statistical mechanical methods is central to this thesis with a small portion devoted to modeling the evolutionary dynamics of positive-sense single-stranded RNA viruses. In order to develop and test models of biopolymer mechanics and illuminate the mechanisms underlying biological processes where biopolymers undergo changes in energy on the order of the thermal energy, , entails measuring forces and lengths on the scale of piconewtons (pN) and nanometers (nm), respectively. A capacity achieved in the past two decades at the single-molecule level through the development of micromanipulation techniques such as magnetic and optical tweezers, atomic force microscopy, coupled with advances in micro- and nanofabrication. The statistical mechanical models of biopolymers developed in this dissertation are dependent upon and the outcome of these advancements and resulting experiments. The dissertation begins in chapter 1 with an introduction to the structure and thermodynamics of DNA and RNA, highlighting the importance and effectiveness of simple, two-state models in their description as a prelude to the emergence of two-state models in the research manuscripts. In chapter 2 the standard models of the elasticity of polymers and of a polymer gel are reviewed, characterizing the continuum and mean-field models, including the scaling behavior of DNA in confined spaces. The research manuscript presented in the last section of chapter 2 (section 2.5), subsequent to a review of a Flory gel and in contrast to it, is a model of the elasticity of RNA as a gel, with viral RNA illustrating an instance of such a network, and shown to exhibit anomalous elastic behavior, a negative Poisson ratio, and capable of facilitating viral RNA encapsidation with further context provided in section 5.1. In chapter 3 the experimental methods and behavior of DNA and RNA under mechanical

  20. Determination of the vertical ground reaction forces acting upon individual limbs during healthy and clinical gait.

    Science.gov (United States)

    Meurisse, Guillaume M; Dierick, Frédéric; Schepens, Bénédicte; Bastien, Guillaume J

    2016-01-01

    In gait lab, the quantification of the ground reaction forces (GRFs) acting upon individual limbs is required for dynamic analysis. However, using a single force plate, only the resultant GRF acting on both limbs is available. The aims of this study are (a) to develop an algorithm allowing a reliable detection of the front foot contact (FC) and the back foot off (FO) time events when walking on a single plate, (b) to reconstruct the vertical GRFs acting upon each limb during the double contact phase (DC) and (c) to evaluate this reconstruction on healthy and clinical gait trials. For the purpose of the study, 811 force measurements during DC were analyzed based on walking trials from 27 healthy subjects and 88 patients. FC and FO are reliably detected using a novel method based on the distance covered by the centre of pressure. The algorithm for the force reconstruction is a revised version of the approach of Davis and Cavanagh [24]. In order to assess the robustness of the algorithm, we compare the resulting GRFs with the real forces measured with individual force plates. The median of the relative error on force reconstruction is 1.8% for the healthy gait and 2.5% for the clinical gait. The reconstructed and the real GRFs during DC are strongly correlated for both healthy and clinical gait data (R(2)=0.998 and 0.991, respectively).

  1. Self-consistent treatment of electrostatics in molecular DNA braiding through external forces.

    Science.gov (United States)

    Lee, Dominic J

    2014-06-01

    In this paper we consider a physical system in which two DNA molecules braid about each other. The distance between the two molecular ends, on either side of the braid, is held at a distance much larger than supercoiling radius of the braid. The system is subjected to an external pulling force, and a moment that induces the braiding. In a model, developed for understanding such a system, we assume that each molecule can be divided into a braided and unbraided section. We also suppose that the DNA is nicked so that there is no constraint of the individual linking numbers of the molecules. Included in the model are steric and electrostatic interactions, thermal fluctuations of the braided and unbraided sections of the molecule, as well as the constraint on the braid linking (catenation) number. We compare two approximations used in estimating the free energy of the braided section. One is where the amplitude of undulations of one molecule with respect to the other is determined only by steric interactions. The other is a self-consistent determination of the mean-squared amplitude of these undulations. In this second approximation electrostatics should play an important role in determining this quantity, as suggested by physical arguments. We see that if the electrostatic interaction is sufficiently large there are indeed notable differences between the two approximations. We go on to test the self-consistent approximation-included in the full model-against experimental data for such a system, and we find good agreement. However, there seems to be a slight left-right-handed braid asymmetry in some of the experimental results. We discuss what might be the origin of this small asymmetry.

  2. Trends and projections of Southern Hemisphere baroclinicity: the role of external forcing and impact on Australian rainfall

    Science.gov (United States)

    Frederiksen, Carsten S.; Frederiksen, Jorgen S.; Sisson, Janice M.; Osbrough, Stacey L.

    2016-07-01

    Changes in the characteristics of Southern Hemisphere (SH) storms, in all seasons, during the second half of the twentieth century, have been related to changes in the annual cycle of SH baroclinic instability. In particular, significant negative trends in baroclinic instability, as measured by the Phillips Criterion, have been found in the region of the climatological storm tracks; a zonal band of significant positive trends occur further poleward. Corresponding to this decrease/increase in baroclinic instability there is a decrease/increase in the growth rate of storm formation at these latitudes over this period, and in some cases a preference for storm formation further poleward than normal. Based on model output from a multi-model ensemble (MME) of coupled atmosphere-ocean general circulation models, it is shown that these trends are the result of external radiative forcing, including anthropogenic greenhouse gases, ozone, aerosols and land-use change. The MME is used in an analysis of variance method to separate the internal (natural) variability in the Phillips Criterion from influences associated with anomalous external radiative forcing. In all seasons, the leading externally forced mode has a significant trend and a loading pattern highly correlated with the pattern of trends in the Phillips Criterion. The covariance between the externally forced component of SH rainfall and the leading external mode strongly resembles the MME pattern of SH rainfall trends. A comparison between similar analyses of MME simulations using the second half of the twenty-first century of the Representative Concentration Pathways (RCP) RCP8.5 and RCP4.5 scenarios show that trends in the Phillips Criterion and rainfall are projected to continue and intensify under increasing anthropogenic greenhouse gas concentrations.

  3. Trends and projections of Southern Hemisphere baroclinicity: the role of external forcing and impact on Australian rainfall

    Science.gov (United States)

    Frederiksen, Carsten S.; Frederiksen, Jorgen S.; Sisson, Janice M.; Osbrough, Stacey L.

    2017-05-01

    Changes in the characteristics of Southern Hemisphere (SH) storms, in all seasons, during the second half of the twentieth century, have been related to changes in the annual cycle of SH baroclinic instability. In particular, significant negative trends in baroclinic instability, as measured by the Phillips Criterion, have been found in the region of the climatological storm tracks; a zonal band of significant positive trends occur further poleward. Corresponding to this decrease/increase in baroclinic instability there is a decrease/increase in the growth rate of storm formation at these latitudes over this period, and in some cases a preference for storm formation further poleward than normal. Based on model output from a multi-model ensemble (MME) of coupled atmosphere-ocean general circulation models, it is shown that these trends are the result of external radiative forcing, including anthropogenic greenhouse gases, ozone, aerosols and land-use change. The MME is used in an analysis of variance method to separate the internal (natural) variability in the Phillips Criterion from influences associated with anomalous external radiative forcing. In all seasons, the leading externally forced mode has a significant trend and a loading pattern highly correlated with the pattern of trends in the Phillips Criterion. The covariance between the externally forced component of SH rainfall and the leading external mode strongly resembles the MME pattern of SH rainfall trends. A comparison between similar analyses of MME simulations using the second half of the twenty-first century of the Representative Concentration Pathways (RCP) RCP8.5 and RCP4.5 scenarios show that trends in the Phillips Criterion and rainfall are projected to continue and intensify under increasing anthropogenic greenhouse gas concentrations.

  4. Strong optical force acting on a dipolar particle over a multilayer substrate

    CERN Document Server

    Wang, Shubo

    2015-01-01

    Optical forces acting on nano-sized particles are typically too small to be useful for particle manipulation. We theoretically and numerically demonstrate a mechanism that can significantly enhance the optical force acting on a small particle through a special type of resonant particle-substrate coupling. The resonance arises from the singular behavior of the particle's effective polarizablity in the presence of a metal-dielectric-metal multilayer substrate. We show that this phenomenon is closely related to the existence of a flat-band plasmon mode supported by the multilayer substrate.

  5. How do the substrate reaction forces acting on a gecko's limbs respond to inclines?

    Science.gov (United States)

    Wang, Zhouyi; Dai, Zhendong; Li, Wei; Ji, Aihong; Wang, Wenbao

    2015-02-01

    Locomotion is an essential character of animals, and excellent moving ability results from the delicate sensing of the substrate reaction forces (SRF) acting on body and modulating the behavior to adapt the motion requirement. The inclined substrates present in habitats pose a number of functional challenges to locomotion. In order to effectively overcome these challenges, climbing geckos execute complex and accurate movements that involve both the front and hind limbs. Few studies have examined gecko's SRF on steeper inclines of greater than 90°. To reveal how the SRFs acting on the front and hind limbs respond to angle incline changes, we obtained detailed measurements of the three-dimensional SRFs acting on the individual limbs of the tokay gecko while it climbed on an inclined angle of 0-180°. The fore-aft forces acting on the front and hind limbs show opposite trends on inverted inclines of greater than 120°, indicating propulsion mechanism changes in response to inclines. When the incline angles change, the forces exerted in the normal and fore-aft directions by gecko's front and hind limbs are reassigned to take full advantage of limbs' different roles in overcoming resistance and in propelling locomotion. This also ensures that weight acts in the angle range between the forces generated by the front and hind limbs. The change in the distribution of SRF with a change in the incline angle is directly linked to the favorable trade-off between locomotive maneuverability and stability.

  6. Prediction of fluid forces acting on a hand model in unsteady flow conditions.

    Science.gov (United States)

    Kudo, Shigetada; Yanai, Toshimasa; Wilson, Barry; Takagi, Hideki; Vennell, Ross

    2008-01-01

    The aim of this study was to develop a method to predict fluid forces acting on the human hand in unsteady flow swimming conditions. A mechanical system consisting of a pulley and chain mechanism and load cell was constructed to rotate a hand model in fluid flows. To measure the angular displacement of the hand model a potentiometer was attached to the axis of the rotation. The hand model was then fixed at various angles about the longitudinal axis of the hand model and rotated at different flow velocities in a swimming flume for 258 different trials to approximate a swimmer's stroke in unsteady flow conditions. Pressures were taken from 12 transducers embedded in the hand model at a sampling frequency of 200Hz. The resultant fluid force acting on the hand model was then determined on the basis of the kinetic and kinematic data taken from the mechanical system at the frequency of 200Hz. A stepwise regression analysis was applied to acquire higher order polynomial equations that predict the fluid force acting on the accelerating hand model from the 12 pressure values. The root mean square (RMS) difference between the resultant fluid force measured and that predicted from the single best-fit polynomial equation across all trials was 5N. The method developed in the present study accurately predicted the fluid forces acting on the hand model.

  7. Influence of external climate forcing on coastal upwelling systems analysed in ensemble of past millennium climate simulations

    Science.gov (United States)

    Tim, Nele; Zorita, Eduardo; Hünicke, Birgit; Yi, Xin; Emeis, Kay

    2016-04-01

    Eastern Boundary Upwelling Systems are highly productive coastal ocean areas where nutrient rich, cold water upwells by the action of favorable winds. Observations over the 20th century and ocean sediment records, which may be indicative of upwelling, display an intensification due to stronger external climate forcing, such as increasing greenhouse gas concentrations or changes in solar irradiance. This intensification is compatible with the hypothesis put forward by Bakun (1990) that a stronger external radiative forcing should lead to a more intense coastal upwelling. Here, we analyze ensemble of simulations covering the past millennium with the aim of identifying and quantifying the role of external climate forcing on upwelling in the major Eastern Boundary Upwelling System. We analyse the decadal variability and centennial trends of upwelling in ensemble of simulations with the global climate model MPI-ESM covering the past millennium, the last 150 years and the next 100 years. The future simulations were driven by three IPCC scenarios of concentrations of anthropogenic greenhouse gases, RCP2.5, RCP4.5 and RCP 8.5. For the past millennium and the last 150 years, coastal upwelling does not show any imprint of external forcing. This result indicates that chaotic internal variability has dominated upwelling intensity in major upwelling regions over the last thousand years and even since industrialisation up to present. For the 21st century, all ensemble members show a consistent and significant intensification of upwelling in the strongest scenario RCP8.5 for the Benguela upwelling region, consistent and significant weakening for Morocco and California, and no significant change for the Peruvian upwelling. Weaker scenarios do not produce consistent long-term trends that are replicated in all ensemble members. The results are confirmed by analysing another ensemble of past millennium simulations with the model CESM-CAM5 (Community Earth System Model

  8. Generalized polarization force acting on dust grains in a dusty plasma

    Science.gov (United States)

    Bentabet, Karima; Mayout, Saliha; Tribeche, Mouloud

    2017-01-01

    The polarization force acting on dust particles in a dusty plasma is revisited within the theoretical framework of the Tsallis statistical mechanics. The generalized nonextensive polarization force expression is derived. As application, the modifications arising in the propagation of dust-acoustic solitary waves, and dust sheath formation are analyzed. Our results should be of wide relevance to explain and interpret the sheath formation and its structure in nonequilibrium plasmas related process such as surface treatments and ion implantation.

  9. [Forces acting on foot soles during stair climbing in healthy probands and in patients with coxarthrosis].

    Science.gov (United States)

    Savvidis, E; von der Decken, C B

    1999-04-01

    We investigated the contact forces acting on the sole of the foot of healthy persons and coxarthrosis patients climbing and descending stairs. The sole contact forces were determined using an experimental set-up comprising a stair construction provided with an integrated measuring step. In healthy subjects, the forces acting on the soles of the feet while climbing stairs were found to be 1.2 times their body weight. With regard to descending stairs, a distinction must be made between "hard" and "soft" walkers. In the case of "hard" walkers, the forces acting on the soles may be as much as 2.6 times body weight. These forces can be reduced by the wearing of shock-absorbing shoes. In coxarthrosis and prostheses-bearing patients, all movements are executed more slowly when climbing or descending stairs, so that only small dynamic forces arise. The greatest loads are about 1.2 times the patient's own weight. In these patients, an effective reduction by shockabsorbing footwear is not possible.

  10. Observation of three-level rectified dipole forces acting on trapped atoms

    Science.gov (United States)

    Grove, T. T.; Duncan, B. C.; Sanchez-Villicana, V.; Gould, P. L.

    1995-06-01

    We have observed rectified dipole forces acting on three-level atoms in the cascade configuration. Laser cooled and trapped rubidium atoms are illuminated with an intense bichromatic standing wave (780 and 776 nm) tuned near resonance with the 5S1/2-->5P3/2-->5D5/2 transitions. The resulting rectified forces produce periodic potential wells (71-μm period), which localize the cold atoms. Experimental results are in reasonable agreement with theoretical predictions. These forces may be useful in atom optics and laser traps.

  11. Error analysis and assessment of unsteady forces acting on a flapping wing micro air vehicle: free flight versus wind-tunnel experimental methods.

    Science.gov (United States)

    Caetano, J V; Percin, M; van Oudheusden, B W; Remes, B; de Wagter, C; de Croon, G C H E; de Visser, C C

    2015-08-20

    An accurate knowledge of the unsteady aerodynamic forces acting on a bio-inspired, flapping-wing micro air vehicle (FWMAV) is crucial in the design development and optimization cycle. Two different types of experimental approaches are often used: determination of forces from position data obtained from external optical tracking during free flight, or direct measurements of forces by attaching the FWMAV to a force transducer in a wind-tunnel. This study compares the quality of the forces obtained from both methods as applied to a 17.4 gram FWMAV capable of controlled flight. A comprehensive analysis of various error sources is performed. The effects of different factors, e.g., measurement errors, error propagation, numerical differentiation, filtering frequency selection, and structural eigenmode interference, are assessed. For the forces obtained from free flight experiments it is shown that a data acquisition frequency below 200 Hz and an accuracy in the position measurements lower than ± 0.2 mm may considerably hinder determination of the unsteady forces. In general, the force component parallel to the fuselage determined by the two methods compares well for identical flight conditions; however, a significant difference was observed for the forces along the stroke plane of the wings. This was found to originate from the restrictions applied by the clamp to the dynamic oscillations observed in free flight and from the structural resonance of the clamped FWMAV structure, which generates loads that cannot be distinguished from the external forces. Furthermore, the clamping position was found to have a pronounced influence on the eigenmodes of the structure, and this effect should be taken into account for accurate force measurements.

  12. Analyzing excitation forces acting on a plate based on measured acoustic pressure.

    Science.gov (United States)

    Wu, Sean F; Zhou, Pan

    2016-07-01

    This paper presents a theoretical study on "seeing" through an elastic structure to uncover the root cause of sound and vibration by using nearfield acoustical holography (NAH) and normal modes expansion. This approach is of generality because vibro-acoustic responses on the surface of a vibrating structure can always be reconstructed, exactly or approximately. With these vibro-acoustic responses, excitation forces acting on the structure can always be determined, analytically or numerically, given any set of boundary conditions. As an example, the explicit formulations for reconstructing time-harmonic excitation forces, including point, line and surface forces, and their arbitrary combinations acting on a rectangular thin plate in vacuum mounted on an infinite baffle are presented. The reason for choosing this example is that the analytic solutions to vibro-acoustic responses are available, and in-depth analyses of results are possible. Results demonstrate that this approach allows one to identify excitation forces based on measured acoustic pressures and reveal their characteristics such as locations, types and amplitudes, as if one could "see" excitation forces acting behind the plate based on acoustic pressure measured on the opposite side. This approach is extendable to general elastic structures, except that in such circumstance numerical results must be sought.

  13. Experimental study on the estimation method of hydrodynamic force acting on floating offshore structures; Futaishiki kaiyo kozobutsu ni kuwawaru ryutairyoku no suiteiho ni kansuru jikkenteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, K.; Kato, S. [Ship Research Inst., Tokyo (Japan); Koterayama, W. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1996-04-10

    In the design of various floating offshore structures (FOS), the functionality, safety and amenity of FOSs were examined by estimating responses of FOSs to environmental external forces such as wave, wind and flow. In this paper, the estimation method of drag acting on the whole FOS was established by combining previous study results on hydrodynamic force acting on various bodies such as Reynolds number effect (RNE), 3-D effect (TDE) and interference effect (IE). This hydrodynamic force was also compared with that obtained from the experiment result on a FOS model for TLP to confirm the applicability of this estimation method. The estimation result on the drag coefficient in steady flow by considering RNE, TDE and IE well agreed with experimental one. The drag coefficient acting on FOSs in heaving could be estimated in practically sufficient accuracy by considering drag acting on not columns but only square columns. The estimation result on the drag coefficient acting on FOSs in surging by considering RNE, TDE and IE well agreed with experimental one. 12 refs., 10 figs., 1 tab.

  14. Theoretical study of enhancing the piezoelectric nanogenerator's output power by optimizing the external force's shape

    Science.gov (United States)

    Xu, Qi; Qin, Yong

    2017-07-01

    The average power is one of the key parameters of piezoelectric nanogenerators (PENGs). In this paper, we demonstrate that the PENG's output can be gigantically improved by choosing driving force with an appropriate shape. When the load resistance is 100 MΩ and the driven forces have a magnitude of 19.6 nN, frequency of 10 Hz, the average power of PENG driven by square shaped force is six orders of magnitude higher than that driven by triangular shaped and sinusoidal shaped forces. These results are of importance for optimizing the average power of the PENGs in practical applications.

  15. Attosecond Electro-Magnetic Forces Acting on Metal Nanospheres Induced By Relativistic Electrons

    Science.gov (United States)

    Lagos, M. J.; Batson, P. E.; Reyes-Coronado, A.; Echenique, P. M.; Aizpurua, J.

    2014-03-01

    Swift electron scattering near nanoscale materials provides information about light-matter behavior, including induced forces. We calculate time-dependent electromagnetic forces acting on 1-1.5 nm metal nanospheres induced by passing swift electrons, finding both impulse-like and oscillatory response forces. Initially, impulse-like forces are generated by a competition between attractive electric forces and repulsive magnetic forces, lasting a few attoseconds (5-10 as). Oscillatory, plasmonic response forces take place later in time, last a few femtoseconds (1- 5 fs), and apparently rely on photon emission by decay of the electron-induced surface plasmons. A comparison of the strength of these two forces suggests that the impulse-like behavior dominates the process, and can transfer significant linear momentum to the sphere. Our results advance understanding of the physics behind the observation of both attractive and repulsive behavior of gold nano-particles induced by electron beams in aberration-corrected electron microscopy. Work supported under DOE, Award # DE-SC0005132, Basque Gov. project ETORTEK inano, Spanish Ministerio de Ciencia e Innovacion, No. FIS2010-19609-C02-01.

  16. Static and Dynamic Performance Simulation of Direct-Acting Force Motor Valve

    Science.gov (United States)

    Ye, Xinghai; Ding, Jianjun; Zheng, Gang; Jiang, Kunpeng; Chen, Dongdong

    2017-07-01

    This work focuses on static and dynamic characteristics of direct-acting force motor valve. First, we analyzed the structure features and operating principle of the Mitsubishi-Hitachi force motor valve (FMV) and the operating principle of its internal permanent-magnet moving-coil force motor magnetic circuit, determined the transfer function of the FMV force motor system, and established a mathematical model for the system. Secondly, we established a static performance analysis model using the AMESIM software and utilized the model in combination with experimental results to analyze the effects of electro-hydraulic servo valve structural parameters on static characteristics. Lastly, we deduced the trajectory equation of the system, established the relationship between dynamic characteristic indexes and structural parameters, and analyzed the effects of different parameter values on the dynamic characteristics of the system. This research can provide a theoretical guidance for designing and manufacturing the FMV body.

  17. The role of external forcing and Pacific trade winds in recent changes of the global climate system

    Science.gov (United States)

    Friedman, Andrew; Gastineau, Guillaume; Khodri, Myriam

    2017-04-01

    The Pacific trade winds experienced an unprecedented strengthening since the mid 1990s. Several studies have proposed that the increased Pacific trade winds were associated with the reduced rate of global mean surface temperature warming in the first decade of the 21st century, as well as far-reaching atmospheric teleconnections. We designed a set of ensemble partial coupling experiments using the IPSL-CM5A-LR coupled model that allow us to cleanly distinguish the influence of Pacific trade wind variability from that of external forcing over the past few decades. In this study, we quantify the respective impacts of these processes on surface temperature, ocean heat content, and atmospheric teleconnections. We designed two ensembles of coupled simulations using partial coupling with the IPSL-CM5A-LR model to separate the Pacific internal variability and that of external radiative forcing. We prescribe surface wind stress in the tropical Pacific (20°S to 20°N) from 1979-2014 in two ensembles of 30 members each: (1) Prescribed climatological model wind stress, which allows us to estimate the influence of external radiative forcing in the absence of variability within the Pacific Ocean. (2) Wind stress anomalies from ERA-Interim reanalysis added to the model wind stress climatology, which accounts for the effects of both external radiative forcing and the wind stress variability. We find that the observed wind stress anomalies account for the pattern of eastern tropical Pacific cooling when compared to the climatology experiment, so that it resembles the observed trends from 1992-2011. The tropical Pacific shows dominant heat uptake in the western Pacific above the 20°C isotherm, which contributed to slow the warming of tropical SST during the 2000s. The trade wind increase is associated with a strengthening of the Pacific Walker circulation, and zonal shifts in tropical rainfall. Despite tropical SST biases which affect the response of tropical rainfall and the

  18. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  19. Analysis of unsteady flow forces acting on the thermowell in a steam turbine control stage

    Science.gov (United States)

    Badur, J.; Kornet, S.; Sławiński, D.; Ziółkowski, P.

    2016-10-01

    In the present paper the phenomenon of unsteady flow forces acting on the thermowell for measuring steam temperature in a steam turbine control stage has been presented. The non-stationarity of fluid acting on the thermowell such as: Strouhal frequency, pressure amplitude, pressure peaks, pressure field, velocity field etc. have been studied analytically and numerically. There have been examined two cases of flow with changing mass flow rate, pressure and temperature in the control stage chamber of a turbine high-pressure cylinder. The problem of entry into resonance by thermowell has been described in the ASME standard PTC19.3 TW-2010 with providing detailed guidelines for thermowell designs.

  20. The acoustic force density acting on inhomogeneous fluids in acoustic fields

    CERN Document Server

    Karlsen, Jonas T; Bruus, Henrik

    2016-01-01

    We present a theory for the acoustic force density acting on inhomogeneous fluids in acoustic fields on time scales that are slow compared to the acoustic oscillation period. The acoustic force density depends on gradients in the density and compressibility of the fluid. For microfluidic systems, the theory predicts a relocation of the inhomogeneities into stable field-dependent configurations, which are qualitatively different from the horizontally layered configurations due to gravity. Experimental validation is obtained by confocal imaging of aqueous solutions in a glass-silicon microchip.

  1. Taking Advantage of External Funding for Air Force Officer PH.D. Candidates at Civilian Universities

    Science.gov (United States)

    2009-12-01

    Education,” http://www.afit.edu/grad.cfm. 21 Clarence W. Hannon et al., “Graduate Education within the Armed Forces,” Group Research Project...Force Line Officers, Research Report no. AFHRL-TR-70-7 (Lackland AFB, TX: Personnel Research Division, 1970). 56 Clarence W. Hannon et al...Bolton, Benjamin F. Findley, William S. Mosley, Lawrence Mwambola, Jeffrey N. Renehan, Glenward L. Spivey, John F. Thompson , Jack Weinstein. ―Air

  2. Decoupled external forces in a predictor-corrector segmentation scheme for LV contours in Tagged MR images.

    Science.gov (United States)

    Garcia-Barnes, Jaume; Andaluz, Albert; Carreras, Francesc; Gil, Debora

    2010-01-01

    Computation of functional regional scores requires proper identification of LV contours. On one hand, manual segmentation is robust, but it is time consuming and requires high expertise. On the other hand, the tag pattern in TMR sequences is a problem for automatic segmentation of LV boundaries. We propose a segmentation method based on a predictor-corrector (Active Contours - Shape Models) scheme. Special stress is put in the definition of the AC external forces. First, we introduce a semantic description of the LV that discriminates myocardial tissue by using texture and motion descriptors. Second, in order to ensure convergence regardless of the initial contour, the external energy is decoupled according to the orientation of the edges in the image potential. We have validated the model in terms of error in segmented contours and accuracy of regional clinical scores.

  3. Flow Field of Metallic Fluid Acted by Electromagnetic and Centrifugal Force

    Institute of Scientific and Technical Information of China (English)

    QIU Yi-qing; LUO Zong-an; JIA Guang-lin; LIU Xiang-hua; WANG Guo-dong

    2004-01-01

    According to the principle of electromagnetism and hydrodynamics, a mathematical model of flow field for metallic fluid acted by electromagnetic and centrifugal forces was established. The calculation results showed that the relative velocity between metallic fluid layers rises and the absolute rotational velocity of metallic fluid falls with the increase of magnetic induction intensity. The increase of centrifugal revolution hardly affects the relative velocity between metallic fluid layers, but can enhance the absolute rotational velocity of metallic fluid.

  4. Forcing a unitary transformation by an external field comparing two approaches based on optimal control theory

    CERN Document Server

    Palao, J P; Palao, Jose P.; Kosloff, Ronnie

    2002-01-01

    A quantum gate is realized by specific unitary transformations operating on states representing qubits. Considering a quantum system employed as an element in a quantum computing scheme, the task is therefore to enforce the pre-specified unitary transformation. This task is carried out by an external time dependent field. Optimal control theory has been suggested as a method to compute the external field which alters the evolution of the system such that it performs the desire unitary transformation. This study compares two recent implementations of optimal control theory to find the field that induces a quantum gate. The first approach is based on the equation of motion of the unitary transformation. The second approach generalizes the state to state formulation of optimal control theory. This work highlight the formal relation between the two approaches.

  5. Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

    Institute of Scientific and Technical Information of China (English)

    FUZun-Tao; LIUShi-Da; LIUShi-Kuo

    2004-01-01

    The cubic nonlinear Schroedinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial cnvelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

  6. Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Da; LIU Shi-Kuo

    2004-01-01

    The cubic nonlinear Schrodinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial envelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

  7. Euler-Poincaré Reduction of Externally Forced Rigid Body Motion

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2004-01-01

    . Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....

  8. Late Pliocene to Pleistocene sensitivity of the Greenland Ice Sheet in response to external forcing and internal feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Sebastian J.; DeConto, Robert M. [University of Massachusetts, Department of Geosciences, Amherst, MA (United States); Pollard, David [Pennsylvania State University, Earth and Environmental Systems Institute, College of Earth and Mineral Sciences, University Park, PA (United States)

    2011-09-15

    The timing and nature of ice sheet variations on Greenland over the last {proportional_to}5 million years remain largely uncertain. Here, we use a coupled climate-vegetation-ice sheet model to determine the climatic sensitivity of Greenland to combined sets of external forcings and internal feedbacks operating on glacial-interglacial timescales. In particular, we assess the role of atmospheric pCO{sub 2}, orbital forcing, and vegetation dynamics in modifying thresholds for the onset of glaciation in late Pliocene and Pleistocene. The response of circum-Arctic vegetation to declining levels of pCO{sub 2} (from 400 to 200 ppmv) and decreasing summer insolation includes a shift from boreal forest to tundra biomes, with implications for the surface energy balance. The expansion of tundra amplifies summer surface cooling and heat loss from the ground, leading to an expanded summer snow cover over Greenland. Atmospheric and land surface fields respond to forcing most prominently in late spring-summer and are more sensitive at lower Pleistocene-like levels of pCO{sub 2}. We find cold boreal summer orbits produce favorable conditions for ice sheet growth, however simulated ice sheet extents are highly dependent on both background pCO{sub 2} levels and land-surface characteristics. As a result, late Pliocene ice sheet configurations on Greenland differ considerably from late Pleistocene, with smaller ice caps on high elevations of southern and eastern Greenland, even when orbital forcing is favorable for ice sheet growth. (orig.)

  9. Quasi-two-layer finite-volume scheme for modeling shallow water flows with the presence of external forces

    CERN Document Server

    Karelsky, K V; Slavin, A G

    2011-01-01

    The numerical method for study of hydrodynamic flows over an arbitrary bed profile in the presence of external force is proposed in this paper. This method takes into account the external force effect, it uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with consideration of features of the flow near the step. A distinctive feature of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach allows to determine the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of kinetic energy dissipation. There are performed the numerical simulations based on the proposed algorithm of various physical phenomena, such as a breakdown of the r...

  10. Improvements in springback control by external force laser-assisted sheet bending of titanium and aluminum alloys

    Science.gov (United States)

    Gisario, A.; Barletta, M.; Venettacci, S.

    2016-12-01

    The present investigation deals with an external-force laser assisted bending process of Grade 2 CP titanium and AA 7075 T6 aluminum sheets. High bending angles, sharp fillet radii and control of springback were achieved by tuning the contact pressure of a hydraulically driven tool with the local and selective heating of the bending zone by irradiation with a high power diode laser. First, the role of laser operational parameters, namely power, scanning speed and number of passes, in metal bending was investigated, allowing to identify the most suitable processing window. Second, a custom-built equipment to measure the bending angle during the forming process, together with the metal temperature, was implemented. Real-time monitoring of the bending angle and temperature allowed to evaluate the continuous evolution of the geometry of the metal substrates during the external force laser-assisted bending process. Experimental results showed both metal sheets could be bent to high angles with very low fillet radii by the appropriate combination of the tooling contact pressure and selective laser heating of the bending zone. Laser heating also reduces the risk of rupture in both metals during bending at high angles, limits the springback extent up to 10 times on titanium and 30 times on aluminum in comparison with conventional bending process and does not affect significantly the visual appearance of the bending zone.

  11. An Examination of the External and Internal Forces that have Shaped the Department of Veterans Affairs

    Science.gov (United States)

    2014-05-22

    vacation to the West coast.65 However, before his death, and in another of his interesting management choices , he selected a highly qualified...of the bonus.98 Congress was more forgiving and recognized the public perception of the Army’s use of force on veterans. They voted to provide a per...Hoover to head the review. Mr. Hoover, a Republican, may have seemed an unusual choice for a Democratic President, but he was a respected organizer

  12. Simplified description of optical forces acting on a nanoparticle in the Gaussian standing wave

    Science.gov (United States)

    Zemánek, Pavel; Jonáš, Alexandr; Liška, Miroslav

    2002-05-01

    We study the axial force acting on dielectric spherical particles smaller than the trapping wavelength that are placed in the Gaussian standing wave. We derive analytical formulas for immersed particles with relative refractive indices close to unity and compare them with the numerical results obtained by generalized Lorenz-Mie theory (GLMT). We show that the axial optical force depends periodically on the particle size and that the equilibrium position of the particle alternates between the standing-wave antinodes and nodes. For certain particle sizes, gradient forces from the neighboring antinodes cancel each other and disable particle confinement. Using the GLMT we compare maximum axial trapping forces provided by the Gaussian standing-wave trap (SWT) and single-beam trap (SBT) as a function of particle size, refractive index, and beam waist size. We show that the SWT produces axial forces at least ten times stronger and permits particle confinement in a wider range of refractive indices and beam waists compared with those of the SBT.

  13. Analysis of the forces acting on the saltating particles in the coupled wind-sand-electricity fields

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the theoretical model describing the saltation of sand particles in the coupled wind-sand- electricity fields, the numerical simulations of the forces acting on saltating particles, such as the aerodynamic drag force, Magnus effect, Saffman force and electrostatic force, are analyzed in com- parison to the gravity force of the particles in the steady windblown sand movement. Furthermore, the laws of the above forces vary with the friction velocity, the diameter of the sand particle, the initial an- gular velocity and the lift-off velocity are discussed.

  14. Analysis of the forces acting on the saltating particles in the coupled wind-sand-electricity fields

    Institute of Scientific and Technical Information of China (English)

    WU JianJun; YAN GuangHu

    2009-01-01

    Based on the theoretical model describing the saltation of sand particles in the coupled wind-sand-electricity fields, the numerical simulations of the forces acting on saltating particles, such as the aerodynamic drag force, Magnus effect, Saffman force and electrostatic force, are analyzed in com-parison to the gravity force of the particles in the steady windblown sand movement. Furthermore, the laws of the above forces vary with the friction velocity, the diameter of the sand particle, the initial an-gular velocity and the lift-off velocity are discussed.

  15. Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

    Directory of Open Access Journals (Sweden)

    E. Katragkou

    2009-05-01

    Full Text Available Regional air quality decadal simulations were carried out using the air quality model CAMx driven off-line by the regional climate model RegCM3 for the time slice 1991–2000 using two different datasets of external meteorological forcing to constrain RegCM3: the ERA40 global atmospheric reanalysis dataset and the output from the GCM ECHAM5. The focus of this work is to compare the perfect lateral boundary conditions experiment with the GCM driven control experiment and to investigate how this external meteorological forcing affects near surface ozone. The different RegCM3 meteorological forcings resulted in changes of near surface ozone over Europe ranging between ±5 ppb for winter and summer, while all model parameterizations and anthropogenic emissions remained unchanged. Changes in near surface ozone are induced by changes in meteorological fields and biogenic emissions, which are on-line calculated and meteorology-dependent. The model simulations suggest that the change in solar radiation is the factor that mostly modulates the ozone changes in summer. During winter season it is found that the induced changes in NOx explain about 40% of the ozone variability. The meteorological induced changes in biogenic emissions are quite low for winter with rather small impact on ozone while they are more temperature than radiation dependent. Using multiple regression analysis to associate the changes in near surface ozone with the respective changes in selected meteorological parameters and ozone precursors, an explained variance of 70% in summer and 60% in winter is reproduced.

  16. Experimental evidence of landscape reorganization under changing external forcing: implications to climate-driven knickpoints

    Science.gov (United States)

    Singh, Arvind; Tejedor, Alejandro; Grimaud, Jean-Louis; Foufoula-Georgiou, Efi

    2017-04-01

    Understanding and quantifying geomorphic and topologic re-organization of landscape in response to changing climatic or tectonic forcing is of scientific and practical interest. Although several studies have addressed the large-scale response (e.g., change in mean relief), studies on the smaller-scale drainage pattern re-organization and quantification of landscape vulnerability to the timing, magnitude, and frequency of changing forcing are lacking. To that goal, a series of controlled laboratory experiments were conducted to study the effect of changing precipitation patterns on landscape evolution at the short and long-time scales. High resolution digital elevation (DEM) both in space and time were measured for a range of rainfall patterns and uplift rates. Results from our study show a distinct signature of the precipitation increase on the probabilistic and geometrical structure of landscape features, evident in widening and deepening of channels and valleys, change in drainage patterns within sub-basins and change in the space-time structure of erosional and depositional events. A spatially explicit analysis of the locus of these erosional and depositional events show an acceleration of erosion in the hillslopes when the rainfall intensity is increased, while the incision in fluvial channels is slowed down exhibiting a sediment-flux dependent behavior. Finally, we document the changes in the longitudinal river profiles with increasing precipitation intensity, revealing the formation of knickpoints at certain confluences where large discontinuities in the ratio Qs/Qw are observed.

  17. The hemodynamic and embolizing forces acting on thrombi--II. The effect of pulsatile blood flow.

    Science.gov (United States)

    Basmadjian, D

    1986-01-01

    A previous analysis (Basmadjian, J. Biomechanics 17, 287-298, 1984) of the embolizing forces acting on thrombi in steady Poiseuille flow has been extended to pulsatile blood flow conditions in the major blood vessels. We show that for incipient and small compact thrombi up to 0.1 mm height, the maximum embolizing stresses can be calculated from the corresponding 'quasi-steady' viscous drag forces and measured maximum wall shear. Their magnitude is from 5 to 30 times (tau w)Max, the maximum wall shear stress during the cardiac cycle in the absence of thrombi. For larger thrombi, inertial and 'history' effects have to be taken into account, leading to embolizing stresses in excess of 100 Pa (1000 dyn cm-2).

  18. Irom Chanu Sharmila and the Movement against Armed Forces Special Powers Act (AFSPA

    Directory of Open Access Journals (Sweden)

    Aparajita Sharma

    2014-02-01

    Full Text Available This paper, through the narratives of activists and Meira Paibis reiterates the slogan—repeal the Armed Forces Special Powers Act (AFSPA, which is draconian and anti-people in spirit. The atroci- ty, which has been meted out on the people of Manipur because of this Act, is a profound viola- tion of human rights. Rape, mindless killings, kidnapping, fake encounters have been normalised by virtue of this Act. The youths have been badly affected due to the conflict emerging out of this Act which treats people in Manipur as ‘objects’ against the imagined boundaries of the Indian na- tion-state for security from the neighbouring nations. In this process, the lived experiences of the people have been pushed to the periphery against the massive motive of the state to protect bor- ders and the imagined nation, which is a direct offshoot of the legacy of colonialism in India. The paper has tried to capture the history of Manipur on a capsule to concretise the struggle of Irom Sharmila and the ‘hopes’ she gives to the people of Manipur for ‘peace’ and ‘justice’. Alongside, it makes a humble attempt to describe the ‘life’ of Irom Sharmila. In addition, it describes the rage of Manipuris, which have given rise to insurgency asking for ‘freedom’ through various platforms.

  19. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012

    DEFF Research Database (Denmark)

    Muresan, Ioana Stefania; Khan, Shfaqat Abbas; Aschwanden, Andy

    thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland......-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly...... warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic...

  20. External forcing of earthquake swarms at Alpine regions: example from a seismic meteorological network at Mt. Hochstaufen SE-Bavaria

    Directory of Open Access Journals (Sweden)

    V. Svejdar

    2011-11-01

    Full Text Available In the last few years, it has been shown that above-average rainfall and the following diffusion of excess water into subsurface structures is able to trigger earthquake swarms in the uppermost brittle portion of the Earth's crust. However, there is still an ongoing debate on whether the crust already needs to be in a critical-to-failure state or whether it is sufficient that water is transported rapidly within channels and veins of karst or similar geological formations to the underlying, earthquake-generating layers. Also unknown is the role of other forcing mechanisms, possible co-variables and probably necessary tectonic loading in the triggering process of earthquakes. Because of these problems, we do not use an explicit physical model but instead analyze the meteorological and geophysical data via sophisticated statistical models. ewline We are interested in the influence of a more complete set of possible forcing parameters, including the influence of synthetic earth tides, on the occurrence of earthquake swarms. In this context, regression models are the adequate tool, since the calculation of simple correlations can be confounded by the other variables. Since our outcome variable (the number of quakes is a count, we use Poisson regression models that include the plausible assumption of a Poisson distribution for the counts. For this study, we use nearly continuous recordings of a seismic and meteorological network in the years 2002–2008 at Mt. Hochstaufen in SE-Bavaria. Our non-linear regression model reveals correlations between external forces and the triggering of earthquakes. In addition to the still dominant influence of rainfall, theoretical estimated tidal tilt show some weak influence on the swarm generation. However, the influence of the modeled trend functions shows that rain is by far not the most important forcing mechanism present in the data.

  1. Effect of external shearing force on exfoliation structure and properties of high-performance epoxy/clay nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LU Hai-jun; ZHANG Bao-yan; CHEN Xiang-bao

    2005-01-01

    To further investigate the influence of organic modifiers (primary amine with catalytic hydrogen and quaternary alkylammonium salt) on exfoliation behavior of clay tactoids, high-speed emulsifying and homogeneous mixing(HEHM) and ball milling were used to exert external shearing force on two organic clay tactoids (termed as MMTDDA and MMTDBDA, respectively), which were organically modified with DoDecyl Amine(DDA) and Dodecyl Benzyl Dimethyl Ammonium chloride(DBDA) ,respectively. The effects of external shearing force on microstructure and properties of both resultant nanocomposites were investigated by X-ray diffractometry(XRD), transmission electron microscopy(TEM) and thermogravimetric analysis(TGA). The results show that whether the clay tactoids are organically modified with catalytic primary amine or quaternary alkylammonium salt, the large agglomerates will not be finely dispersed or exfoliated by conventional mixing (magnetic stirring). After being vigorously sheared by HEHM or ball milling, the dispersion and exfoliation of clay tactoids are increasingly promoted for both MMTDDA and MMTDBDA, and the mechanical properties of the high-performance epoxy/clay nanocomposites are enhanced. For epoxy/MMTDDA nanocomposites, impact strength can be increased up to 44.5 kJ/m2 from 32.1 kJ/m2 , which is about 39% higher than that of pristine matrix, and the flexural strength is enhanced by about 4%. A similar enhancement for epoxy/MMTDBDA nanocomposites has also been achieved. Improvement on thermal stability of epoxy/clay nanocomposites is dependent on the exfoliation of clay layers and molecular structure of the modifiers. The onset temperature is increased with the clay loading decreasing from 5% or higher content to 3% (mass fraction), and the DBDA modifier with the heat-resistant benzyl may also improve the stability of epoxy/MMTDBDA nanocomposites.

  2. The importance of ENSO nonlinearities in tropical pacific response to external forcing

    Science.gov (United States)

    Karamperidou, Christina; Jin, Fei-Fei; Conroy, Jessica L.

    2016-12-01

    Tropical Pacific climate varies at interannual, decadal and centennial time scales, and exerts a significant influence on global climate. Climate model projections exhibit a large spread in the magnitude and pattern of tropical Pacific warming in response to greenhouse-gas forcing. Here, we show that part of this spread can be explained by model biases in the simulation of interannual variability, namely the El Niño/Southern Oscillation (ENSO) phenomenon. We show that models that exhibit strong ENSO nonlinearities simulate a more accurate balance of ENSO feedbacks, and their projected tropical Pacific sea surface temperature warming pattern is closely linked to their projected ENSO response. Within this group, models with ENSO nonlinearity close to observed project stronger warming of the cold tongue, whereas models with stronger than observed ENSO nonlinearity project a more uniform warming of the tropical Pacific. These differences are also manifest in the projected changes of precipitation patterns, thereby highlighting that ENSO simulation biases may lead to potentially biased projections in long-term precipitation trends, with great significance for regional climate adaptation strategies.

  3. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    Science.gov (United States)

    Brandl, Martin; Mayer, Michael; Hartmann, Jens; Posnicek, Thomas; Fabian, Christian; Falkenhagen, Dieter

    2010-09-01

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  4. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    Energy Technology Data Exchange (ETDEWEB)

    Brandl, Martin, E-mail: martin.brandl@donau-uni.ac.a [Center for Biomedical Technology, Danube University Krems, Krems (Austria); Mayer, Michael [University of Applied Sciences, St. Poelten (Austria); Hartmann, Jens; Posnicek, Thomas [Center for Biomedical Technology, Danube University Krems, Krems (Austria); Fabian, Christian [University of Applied Sciences, St. Poelten (Austria); Falkenhagen, Dieter [Center for Biomedical Technology, Danube University Krems, Krems (Austria)

    2010-09-15

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  5. Sensitivity of oxygen dynamics in the water column of the Baltic Sea to external forcing

    Directory of Open Access Journals (Sweden)

    S. Miladinova

    2010-04-01

    Full Text Available A 1-D biogeochemical/physical model of marine systems has been applied to study the oxygen cycle in four stations of different sub-basins of the Baltic Sea, namely, in the Gotland Deep, Bornholm, Arkona and Fladen. The model consists of the biogeochemical model of Neumann et al. (2002 coupled with the 1-D General Ocean Turbulence Model (GOTM. The model has been forced with meteorological data from the ECMWF reanalysis project for the period 1998–2003, producing a six year hindcast which is validated with datasets from the Baltic Environmental Database (BED for the same period. The vertical profiles of temperature and salinity are relaxed towards both profiles provided by 3-D simulations of General Estuarine Transport Model (GETM and observed profiles from BED. Modifications in the parameterisation of the air-sea oxygen fluxes have led to a significant improvement of the model results in the surface and intermediate water layers. The largest mismatch with observations is found in simulating the oxygen dynamics in the Baltic Sea bottom waters. The model results demonstrate the good capability of the model to predict the time-evolution of the physical and biogeochemical variables at all different stations. Comparative analysis of the modelled oxygen concentrations with respect to observation data is performed to distinguish the relative importance of several factors on the seasonal, interannual and long-term variations of oxygen. It is found that natural physical factors, like the magnitude of the vertical turbulent mixing, wind speed and the variation of temperature and salinity fields are the major factors controlling the oxygen dynamics in the Baltic Sea. The influence of limiting nutrients is less pronounced, at least under the nutrient flux parameterisation assumed in the model.

  6. Helix-like biopolymers can act as dampers of force for bacteria in flows.

    Science.gov (United States)

    Zakrisson, Johan; Wiklund, Krister; Axner, Ove; Andersson, Magnus

    2012-06-01

    Biopolymers are vital structures for many living organisms; for a variety of bacteria, adhesion polymers play a crucial role for the initiation of colonization. Some bacteria express, on their surface, attachment organelles (pili) that comprise subunits formed into stiff helix-like structures that possess unique biomechanical properties. These helix-like structures possess a high degree of flexibility that gives the biopolymers a unique extendibility. This has been considered beneficial for piliated bacteria adhering to host surfaces in the presence of a fluid flow. We show in this work that helix-like pili have the ability to act as efficient dampers of force that can, for a limited time, lower the load on the force-mediating adhesin-receptor bond on the tip of an individual pilus. The model presented is applied to bacteria adhering with a single pilus of either of the two most common types expressed by uropathogenic Escherichia coli, P or type 1 pili, subjected to realistic flows. The results indicate that for moderate flows (~25 mm/s) the force experienced by the adhesin-receptor interaction at the tip of the pilus can be reduced by a factor of ~6 and ~4, respectively. The uncoiling ability provides a bacterium with a "go with the flow" possibility that acts as a damping. It is surmised that this can be an important factor for the initial part of the adhesion process, in particular in turbulent flows, and thereby be of use for bacteria in their striving to survive a natural defense such as fluid rinsing actions.

  7. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012

    Science.gov (United States)

    Muresan, I. S.; Khan, S. A.; Aschwanden, A.; Khroulev, C.; Bjork, A. A.; Box, J. E.

    2014-12-01

    Greenland's main outlet glaciers have more than doubled their contribution to global sea-level rise over the past decade through acceleration of ice discharge. One of the triggering mechanisms is a reduction in resistance (buttressing) at the marine based glacier front (i.e. through reduced thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland, but the controlling processes and triggering mechanisms are still unclear. Furthermore, our current understanding is almost entirely based on observations from a short-term record spanning only from a year to a decade, and is characterized by short-term fluctuations and therefore not representative for longer-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic oscillation (NAO) winter index and the Atlantic multidecadal oscillation (AMO) index anomalies for the period 1900-2012 sustain our modelling results. The modelled surface elevation changes near the front are considered and compared with observed surface elevation changes for the period 1880-2012. Furthermore, the modelled mass loss signal between 1997-2012 is validated based on ice mass change observations which we estimate using altimeter surveys from NASA's ATM flights during 1997

  8. Drag and Lift Force Acting on a Rotational Spherical Particle in a Logarithmic Boundary Flow

    Institute of Scientific and Technical Information of China (English)

    XU Wei-jiang; CHE De-fu; XU Tong-mo

    2006-01-01

    The drag and lift forces acting on a rotational spherical particle in a logarithmic boundary flow are numerically studied. The effects of the drag velocity and rotational speed of the sphere on the drag force are examined for the particle Reynolds number from 50 to 300 and for the dimensionless rotational angular speed of 0≤Ω≤1.0. The influence of dimensionless roughness height z0of the wall is also evaluated for z0≤10. The results show that the drag forces on a sphere both in a logarithmic flow and in a uniform unsheared flow increase with the increase of the drag velocity. For 50≤Rep≤300, the drag coefficient (-C)D increases with decreased roughness height z0. The time-averaged drag coefficient is also significantly affected by rotational speed of the sphere and roughness height z0 . The lift coefficient -CL increases with increased rotational speed and decreases with increased roughness height.

  9. Forces acting on particles in a Pelton bucket and similarity considerations for erosion

    Science.gov (United States)

    Rai, A. K.; Kumar, A.; Staubli, T.

    2016-11-01

    High sediment transport rates cause severe erosion issues in hydropower plants leading to interruptions in power generation, decrease in efficiency and shutdown for repair and maintenance. For Pelton turbines operating at high head, the issue of erosion is severe, especially in components like buckets, nozzle rings and needles. Goal of the study is to develop erosion focussed guidelines for both designing as well as operating hydropower plants with Pelton runners. In this study, the flow of sediment inside a Pelton bucket with respect to forces acting on solid particles is analysed with an analytical approach by considering different dynamic forces originating from the rotation of the turbine, the curvature of the buckets, and the Coriolis effect. Further, the path of sediment particles and its effect on erosion phenomena are analysed based on the process of separation of different sized sediment particles from streamlines. The data relating to head, power, discharge, number of jet and efficiency of 250 hydropower plants installed all over the world were analysed in this study to find the major factors related to erosion in Pelton turbine bucket. From analysis of different force ratios, it is found that an increase of D/B, i.e. the ratio of pitch circle diameter and bucket width, and/or decrease of specific speed (nq) enhances erosion. As the erosion process depends significantly on nondimensional parameters D/B and nq, these are considered as similarity measures for scaling of the erosion process in the Pelton buckets of various sizes.

  10. RESEARCH ON WAVE FORCES ACTING ON THE UNIT LENGTH OF A VERITICAL BREAKWATER BY TESTS AND A NUMERICAL MODEL

    Institute of Scientific and Technical Information of China (English)

    HU Jin-peng; YU Yu-xiu; ZHU Liang-sheng

    2006-01-01

    Comprehensive 3D model tests and numerical simulation were performed to study the effects of wave obliquity and multidirectionality on the wave forces acting on vertical breakwaters.The variation of wave forces acting on the unit length of a breakwater was analyzed, and the results were compared with Goda's formula.A numerical model based on a short-crest wave system was used to model regular wave forces for practical use, which showed good results for those waves with small incident angles.

  11. Molecular dynamics study of response of liquid N,N-dimethylformamide to externally applied electric field using a polarizable force field

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Weimin; Niu, Haitao; Lin, Tong; Wang, Xungai; Kong, Lingxue [Institute for Frontier Materials, Deakin University, Waurn Ponds VIC 3216 (Australia)

    2014-01-28

    The behavior of Liquid N,N-dimethylformamide subjected to a wide range of externally applied electric fields (from 0.001 V/nm to 1 V/nm) has been investigated through molecular dynamics simulation. To approach the objective the AMOEBA polarizable force field was extended to include the interaction of the external electric field with atomic partial charges and the contribution to the atomic polarization. The simulation results were evaluated with quantum mechanical calculations. The results from the present force field for the liquid at normal conditions were compared with the experimental and molecular dynamics results with non-polarizable and other polarizable force fields. The uniform external electric fields of higher than 0.01 V/nm have a significant effect on the structure of the liquid, which exhibits a variation in numerous properties, including molecular polarization, local cluster structure, rotation, alignment, energetics, and bulk thermodynamic and structural properties.

  12. The generalized Langevin equation revisited: Analytical expressions for the persistence dynamics of a viscous fluid under a time dependent external force

    Science.gov (United States)

    Olivares-Rivas, Wilmer; Colmenares, Pedro J.

    2016-09-01

    The non-static generalized Langevin equation and its corresponding Fokker-Planck equation for the position of a viscous fluid particle were solved in closed form for a time dependent external force. Its solution for a constant external force was obtained analytically. The non-Markovian stochastic differential equation, associated to the dynamics of the position under a colored noise, was then applied to the description of the dynamics and persistence time of particles constrained within absorbing barriers. Comparisons with molecular dynamics were very satisfactory.

  13. Calculation of the static forces acting on ACV bag-finger skirts

    Science.gov (United States)

    Xie, Y. N.; Hua, Y.

    A mathematical model of the geometry formation of an ACV bag-finger skirt is developed to determine skirt shape and its deflection for varying cushion pressures, and calculations for the reactions of supports of the rigid structure on the skirt at the inner and outer attachment points are obtained. The model assumption that the finger triangle of the two-dimensional bag-finger skirt turns around the inner attachment point with changing ratio of cushion pressure to bag pressure is confirmed by experiments using skirt rigs. Good agreement is found between theoretical and experimental results, and it is shown that when the cushion pressure is changing, the pressure ratio is the essential dimensionless parameter for the skirt geometry formation and its deflection, and for the forces acting on it.

  14. A SIMPLIFIED THEORY FOR UNSTEADY AERODYNAMIC FORCES ACTING ON AN AIRFOIL FLYING ABOVE SEA-WAVES

    Institute of Scientific and Technical Information of China (English)

    SHENG Qi-hu; WU De-ming; ZHANG Liang

    2004-01-01

    A simplified theoretical method based on the quasi-steady wing theory was proposed to study the unsteady aerodynamic forces acting on an airfoil flying in non-uniform flow. Comparison between the theoretical results and the numerical results based on nonlinear theory was made. It shows that the simplified theory is a good approximation for the investigation of the aerodynamic characteristics of an airfoil flying above sea-waves. From on the simplified theory it is also found that an airfoil can get thrust from a wave-disturbed airflow and thus the total drag is reduced. And the relationship among the thrust, the flying altitude, the flying speed and the wave parameters was worked out and discussed.

  15. Study on distribution rule of sliding pushing force and remnant resistant sliding force acting on anti-sliding pile

    Institute of Scientific and Technical Information of China (English)

    Qingyang YU; Lei NIE

    2006-01-01

    Anti-slide pile is one of the important methods to administer landslide geological disaster because of its advantages. It plays important role in administering landslide. It is a premise of reasonable economy and technological advance to know the distribution rule and feature of the force between anti-sliding pile and surrounding rock. To determine the sliding force and remnant resistant sliding force, according to need of study, this paper sets up the geological model and mechanics model in term of a typical landslide, and analyzes the effect rule of sliding body distortion, strength and gravity to the pushing force and remnant resistant sliding force by use of the numerical model. The distribution rule of pushing force and remnant resistant sliding force of the type of landslide is given.

  16. Micro-acting Force in Boundary Layer in Low-Permeability Porous Media

    Institute of Scientific and Technical Information of China (English)

    FENG Yu-Liang; ZHANG Yuan; JI Bing-Yu; MU Wen-Zhi

    2011-01-01

    There are lots of reasons to restrict a low-permeability oil layer to enhance the recovery factor.Based on the research results of non-Darcy flow, microflow of water drive and micro-acting force in low permeability porous media are studied by establishing the expression of fluid viscosity factor.Numerical calculation shows that under the condition of L/S interaction, the radial velocity distribution near the solid wall changes obviously, and the curve form changes from convex to concave.The tinier the capillary radius is, the stronger the L/S interaction is.The larger the n value is, more obvionsly the flowing velocity decreases.The results will help people to deal with improving recovery factor of low permeability reservoir, and understanding the fluid flow behavior in blood capillary.%@@ There are lots of reasons to restrict a low-permeability oil layer to enhance the recovery factor.Based on the research results of non-Darcy flow, microfiow of water drive and micro-acting force in low permeability porous media are studied by establishing the expression of fluid viscosity factor.Numerical calculation shows that under the condition of L/S interaction, the radial velocity distribution near the solid wall changes obviously, and the curve form changes from convex to concave.The tinier the capillary radius is, the stronger the L/S interaction is.The larger the n value is, more obviously the flowing velocity decreases.The results will help people to deal with improving recovery factor of low permeability reservoir, and understanding the fluid How behavior in blood capillary.

  17. Orbital motion in generalized static fields of FELs accounting for axial magnetic field, beam forces, undulator and external focusing

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    1995-12-31

    Various types of undulators with or without axial magnetic field are used in FELs. Supplementary beam focusing can be applied by wedging, inclining or profiling pole faces of plan undulators or superposing external focusing magnetic fields in addition to undulator own focusing. Space-charge forces influence significantly particle motion in high-current, low-energy electron beams. Finally, one can use simultaneously two or more different undulators for some specific purpose: more efficient and selective higher harmonics generation, changing polarization types and direction, gain enhancement in double-period undulator etc. All these cases can be treated by solving the generalized equations of transverse orbital motion in a linear approximation, which is widely used for orbit calculation, gives sufficient accuracy for practical purposes and allows to consider many variants and optimize the chosen one. The undulator field is described as a field of two plane undulators with mutually orthogonal fields and an arbitrary axial (phase) shift between them. Various values of the phase shift correspond to right- or left-handed helical undulators, plane undulator of different polarization etc. The general formulae are reduced to forms that allow easier examination of particular cases: planar or helical undulator combined with axial magnetic field or without it, gyroresonance, limiting beam current, polarization etc.

  18. Establishment and validation of standardized animal models of spinal cord injury by normal external force-caused fracture dislocation

    Institute of Scientific and Technical Information of China (English)

    Weibing Shuang; Qiang Liu; Shoubin Jiao; Yang Yang

    2011-01-01

    The duplication of animal models plays a key role in spinal cord injury research; however, there has been limited study into normal, external force-derived fracture dislocation. This study adopted experimental devices, designed in-house, to construct standardized ventral and dorsal spinal cord injury animal models of 6 g and 17 g falling from a height of 2, 4, and 10 cm, and 15, 30 or 50 g transversal compression on the spinal cord. The results showed that gradual increases in the degree of histopathological injury led to decreased Tarlov and Basso, Beattie and Bresnahan scores for the behavioral test, and increased Ashworth scores for the hind limb. Furthermore, there was a gradual decline in the slope test in the rats with dorsal spinal cord injury that correlated to increases in the falling substance weight or falling height. Similar alterations were observed in the ventral spinal cord injured rats, proportional to the increase in compression weight. Our experimental findings indicate that the standardized experimental rat models of dorsal and ventral spinal cord injury are stable, reliable and reproducible.

  19. Experimental investigation of drag force, Magnus force and drag torque acting on rough sphere moving in calm water

    OpenAIRE

    Lukerchenko, N. (Nikolay); Keita, I. (Ibrahima); Chára, Z. (Zdeněk); Vlasák, P. (Pavel)

    2010-01-01

    The paper describes the results of experiments with a rotating golf ball moving quasi-steadily in calm water. The motion of the ball was recorded on a digital video camera. The dimensionless drag force, Magnus force, and drag torque coefficients were determined from the comparison of the calculated translational and angular velocities and trajectory with experimental ones for the rough particle. The proper value of the correction coefficients were established from condition of the best fittin...

  20. Antidepressant-like effect of centrally acting non-narcotic antitussive caramiphen in a forced swimming test.

    Science.gov (United States)

    Kawaura, Kazuaki; Miki, Risa; Shima, Eriko; Honda, Sokichi; Soeda, Fumio; Shirasaki, Tetsuya; Takahama, Kazuo

    2010-09-13

    Recently, we reported that a centrally acting non-narcotic antitussive (cough suppressant drug), tipepidine produces an antidepressant-like effect in the forced swimming test in rats. Because pharmacological properties of tipepidine apparently differ from those of typical antidepressants developed to date, we speculated that caramiphen, another centrally acting antitussive, has an antidepressant-like effect. That effect of caramiphen was studied in rats using the forced swimming test. Caramiphen at 20 and 40mg/kg i.p. significantly reduced immobility. At 40mg/kg i.p., it increased climbing behavior. Even at 40mg/kg, this drug had no effect on locomotor activity. Results suggest that a centrally acting antitussive possessing inhibition of GIRK channels has an antidepressant-like effect.

  1. The CSIRO Mk3L climate system model version 1.0 – Part 2: Response to external forcings

    Directory of Open Access Journals (Sweden)

    S. J. Phipps

    2012-05-01

    Full Text Available The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulation and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. It is freely available to the research community. This paper evaluates the response of the model to external forcings which correspond to past and future changes in the climate system.

    A simulation of the mid-Holocene climate is performed, in which changes in the seasonal and meridional distribution of incoming solar radiation are imposed. Mk3L correctly simulates increased summer temperatures at northern mid-latitudes and cooling in the tropics. However, it is unable to capture some of the regional-scale features of the mid-Holocene climate, with the precipitation over Northern Africa being deficient. The model simulates a reduction of between 7 and 15% in the amplitude of El Niño-Southern Oscillation, a smaller decrease than that implied by the palaeoclimate record. However, the realism of the simulated ENSO is limited by the model's relatively coarse spatial resolution.

    Transient simulations of the late Holocene climate are then performed. The evolving distribution of insolation is imposed, and an acceleration technique is applied and assessed. The model successfully captures the temperature changes in each hemisphere and the upward trend in ENSO variability. However, the lack of a dynamic vegetation scheme does not allow it to simulate an abrupt desertification of the Sahara.

    To assess the response of Mk3L to other forcings, transient simulations of the last millennium are performed. Changes in solar irradiance, atmospheric greenhouse gas concentrations and volcanic emissions are applied to the model. The model is again broadly successful at simulating larger-scale changes in the

  2. Force

    CERN Document Server

    Graybill, George

    2007-01-01

    Forces are at work all around us. Discover what a force is, and different kinds of forces that work on contact and at a distance. We use simple language and vocabulary to make this invisible world easy for students to ""see"" and understand. Examine how forces ""add up"" to create the total force on an object, and reinforce concepts and extend learning with sample problems.

  3. Numerical Analysis of Dynamic Force Acting Perpendicularly on a Wall Made of Concrete Blocks with Rubber Inserts

    Directory of Open Access Journals (Sweden)

    Major Maciej

    2016-12-01

    Full Text Available In this paper numerical analysis considering the influence of dynamical force acting on wall made of concrete blocks with rubber inserts is presented. By examining the stress values on front and back surface of the analysed wall structure model, the effectiveness of proposed solution can be measured comparing to the wall made of concrete blocks without rubber inserts. Complete numerical analysis was performed in ADINA program.

  4. STUDY OF STATIC AND DYNAMIC STABILITY OF THIN-WALLED BARS EXCITED BY PERIODICAL AXIAL EXTERNAL FORCES.

    Directory of Open Access Journals (Sweden)

    Minodora Maria PASĂRE

    2010-10-01

    Full Text Available In these paper, starting from the relations for the displacements and spinning the transversal section of a bar with thin walls of sections opened expressed by the corresponding influence functions and introducing the components of the exterior forces distributed and the moments of the exterior forces distributed due to the inertia forces, the exciting axial forces together with the following effect of these and of the reaction forces of the elastic environment for leaning it may reach to the system of the equations of parametric vibrations under the form of three integral equation These equations may serve for the study of vibrations of the bars, to study the static stability and to study the dynamic stability

  5. Random three-dimensional jammed packings of elastic shells acting as force sensors.

    Science.gov (United States)

    Jose, Jissy; van Blaaderen, Alfons; Imhof, Arnout

    2016-06-01

    In a jammed solid of granular particles, the applied stress is in-homogeneously distributed within the packing. A full experimental characterization requires measurement of all the interparticle forces, but so far such measurements are limited to a few systems in two and even fewer in three dimensions. Particles with the topology of (elastic) shells are good local force sensors as relatively large deformations of the shells result from relatively small forces. We recently introduced such fluorescent shells as a model granular system in which force distributions can be determined in three dimensions using confocal microscopy and quantitative image analysis. An interesting aspect about these shells that differentiates them from other soft deformable particles is their buckling behavior at higher compression. This leads to deformations that do not conserve the inner volume of the particle. Here we use this system to accurately measure the contact forces in a three-dimensional packing of shells subjected to a static anisotropic compression and to shear. At small deformations forces are linear, however, for a buckled contact, the restoring force is related to the amount of deformation by a square root law, as follows from the theory of elasticity of shells. Near the unjamming-jamming transition (point J), we found the probability distribution of the interparticle forces P(f) to decay nearly exponentially at large forces, with little evidence of long-range force chains in the packings. As the packing density is increased, the tail of the distribution was found to crossover to a Gaussian, in line with other experimental and simulation studies. Under a small shear strain, up to 0.216, applied at an extremely low shear rate, we observed a shear-induced anisotropy in both the pair correlation function and contact force network; however, no appreciable change was seen in the number of contacts per particle.

  6. Random three-dimensional jammed packings of elastic shells acting as force sensors

    Science.gov (United States)

    Jose, Jissy; van Blaaderen, Alfons; Imhof, Arnout

    2016-06-01

    In a jammed solid of granular particles, the applied stress is in-homogeneously distributed within the packing. A full experimental characterization requires measurement of all the interparticle forces, but so far such measurements are limited to a few systems in two and even fewer in three dimensions. Particles with the topology of (elastic) shells are good local force sensors as relatively large deformations of the shells result from relatively small forces. We recently introduced such fluorescent shells as a model granular system in which force distributions can be determined in three dimensions using confocal microscopy and quantitative image analysis. An interesting aspect about these shells that differentiates them from other soft deformable particles is their buckling behavior at higher compression. This leads to deformations that do not conserve the inner volume of the particle. Here we use this system to accurately measure the contact forces in a three-dimensional packing of shells subjected to a static anisotropic compression and to shear. At small deformations forces are linear, however, for a buckled contact, the restoring force is related to the amount of deformation by a square root law, as follows from the theory of elasticity of shells. Near the unjamming-jamming transition (point J ), we found the probability distribution of the interparticle forces P (f ) to decay nearly exponentially at large forces, with little evidence of long-range force chains in the packings. As the packing density is increased, the tail of the distribution was found to crossover to a Gaussian, in line with other experimental and simulation studies. Under a small shear strain, up to 0.216, applied at an extremely low shear rate, we observed a shear-induced anisotropy in both the pair correlation function and contact force network; however, no appreciable change was seen in the number of contacts per particle.

  7. A method for calculation of forces acting on air cooled gas turbine blades based on the aerodynamic theory

    Directory of Open Access Journals (Sweden)

    Grković Vojin R.

    2013-01-01

    Full Text Available The paper presents the mathematical model and the procedure for calculation of the resultant force acting on the air cooled gas turbine blade(s based on the aerodynamic theory and computation of the circulation around the blade profile. In the conducted analysis was examined the influence of the cooling air mass flow expressed through the cooling air flow parameter λc, as well as, the values of the inlet and outlet angles β1 and β2, on the magnitude of the tangential and axial forces. The procedure and analysis were exemplified by the calculation of the tangential and axial forces magnitudes. [Projekat Ministarstva nauke Republike Srbije: Development and building the demonstrative facility for combined heat and power with gasification

  8. Experimental Study and System Identification of Hydrodynamic Force Acting on Heave Damping Plate

    Institute of Scientific and Technical Information of China (English)

    JI Heng-teng; FAN Ju; HUANG Xiang-lu

    2008-01-01

    Although Morison equation is often applied for simulating hydrodynamic force of marine structure, it may give poor results when non-linear behavior is severe or random wave is encountered. This leads to some modifications of Morison equation or other methods for predicting hydrodynamic force. One of them is the system identification technique. In this paper, NARMAX model theory is firstly used to identify the hydrodynamic system of heave damping plates, which are commonly installed on spar platform. Both linear and non-linear models are obtained. The comparisons between the predicted results and measured data indicate that NARMAX model can predict hydrodynamic force of a heave damping plate very well. The measured data for identification originate from forced oscillation tests, which are random records with given spectrum. The forced oscillation forms in experiment also contain simple harmonic, multi-frequency ones.

  9. Forces acting on a single particle in an evaporating sessile droplet on a hydrophilic surface.

    Science.gov (United States)

    Jung, Jung-yeul; Kim, Young Won; Yoo, Jung Yul; Koo, Junemo; Kang, Yong Tae

    2010-02-01

    The evaporating sessile droplet of a mono/didisperse colloid on a plate is a very useful and handy technique in micro/nano/bioapplications to separate, pattern, and control the particles. Although the fundamental nature of the evaporation phenomena and its applications have been extensively proposed, the crucial forces affecting a single particle motion in an evaporating droplet are not reported yet. To elucidate the impact of various forces including the drag, electrostatic, van der Waals, and surface tension forces on the particle motion in suspension, the magnitudes of them are compared using the scale analysis. In the early stage of the evaporation, in which the contact line is fixed, the motion of a single particle suspended in liquid are mostly affected by drag force. Later, with the incidence of the contact line recession, the surface tension force takes over the control of the single particle motion.

  10. Process evaluation to explore internal and external validity of the "Act in Case of Depression" care program in nursing homes.

    NARCIS (Netherlands)

    Leontjevas, R.; Gerritsen, D.L.; Koopmans, R.T.C.M.; Smalbrugge, M.; Vernooij-Dassen, M.J.F.J.

    2012-01-01

    BACKGROUND: A multidisciplinary, evidence-based care program to improve the management of depression in nursing home residents was implemented and tested using a stepped-wedge design in 23 nursing homes (NHs): "Act in case of Depression" (AiD). OBJECTIVE: Before effect analyses, to evaluate AiD proc

  11. Experimental and Numerical Investigation of Radial Forces Acting on Centrifugal Pump Impeller

    Directory of Open Access Journals (Sweden)

    Karaskiewicz Krzysztof

    2014-12-01

    Full Text Available The paper presents the results of measurements and predictions of radial thrust in centrifugal pump with specific speed ns = 26. In the pump tested, a volute with rectangular cross-section was used. The tests were carried out for several rotational speeds, including speeds above and below the nominal one. Commercial code ANSYS Fluent was used for the calculations. Apart from the predictions of the radial force, the calculations of axial thrust were also conducted, and correlation between thrust and the radial force was found. In the range of the measured rotational speeds, similarity of radial forces was checked.

  12. Forces acting on a small particle in an acoustical field in a thermoviscous fluid

    DEFF Research Database (Denmark)

    Karlsen, Jonas Tobias; Bruus, Henrik

    2015-01-01

    -sized particles. For particles of size comparable to or smaller than the boundary layers, the thermoviscous theory leads to profound consequences for the acoustic radiation force. Not only do we predict forces orders of magnitude larger than expected from ideal-fluid theory, but for certain relevant choices...... of materials, we also find a sign change in the acoustic radiation force on different-sized but otherwise identical particles. These findings lead to the concept of a particle-size-dependent acoustophoretic contrast factor, highly relevant to acoustic separation of microparticles in gases, as well...

  13. The European External Action Service: Torn Apart Between Several Principals or Acting as a Smart ‘Double-agent’?

    Directory of Open Access Journals (Sweden)

    Thomas E Henökl

    2014-11-01

    Full Text Available The European External Action Service (EEAS is a hybrid and compound institutional actor in the EU’s multi-level administration with delegated authority from the member states (MS to conduct the EU’s external action. Substantial competences, notably in the field of Neighbourhood and Trade policies, as well as Development and Cooperation remain under the control of the European Commission (Commission. At the same time, also Members of the European Parliament (EP are more clearly voicing their interests and ownership in the EU’s representation in the world. This article tests the notion of 'double-agent' – or in fact “triple-agent” – as a way of characterizing the position of the EEAS, and in particular of the EU Delegations (as the ‘EU field-level bureaucracies’ vis-à-vis the MS, the Commission and the EP, as an expression of complex and interrelated chains of delegation, where the EU ‘embassies‘ have to interact with and to answer to (but not in a clear line of delegation different (sets of principals, namely the MS, the Commission and the EP. Based on the findings from a series of elite interviews with 47 EEAS and Commission officials and on a survey among 184 EU diplomats, the paper seeks to examine this fuzzy principal-agent relationship and uses the review process of the EEAS as an opportunity to assess the level of autonomy of the new EU foreign policy apparatus.

  14. The solution of a wedge disclination dipole interacting with an annular inclusion and the force acting on the disclination dipole

    Institute of Scientific and Technical Information of China (English)

    Song Hao-Peng; Fang Qi-Hong; Liu You-Wen

    2008-01-01

    The interaction between a wedge disclination dipole and an elastic annular inclusion is investigated. Utilizing the Muskhelishvili complex variable method, the explicit series form solutions of the complex potentials in the matrix and the inclusion region are derived. The image force acting on the disclination dipole centre is also calculated. The influence of the location of the disclination dipole and the thickness of the annular inclusion as well as the elastic dissimilarity of materials upon the equilibrium position of the disclination dipole is discussed in detail. The results show that a stable equilibrium point of the disclination dipole near the inclusion is found for certain combinations of material constant.Moreover, the force on the disclination dipole is strongly affected by the position of the disclination dipole and the thickness of annular inclusion. The repulsion force increases (or the attraction force reduces) with the increase of the thickness of the annular inclusion. An appropriate critical value of the thickness of the annular inclusion may be found to change the direction of the force on the disclination dipole. The present solutions include previous results as special cases.

  15. Experimental Study of the Forces Acting on the Tool in the Friction-Stir Welding of AA 2024 T3 Sheets

    Science.gov (United States)

    Astarita, A.; Squillace, A.; Carrino, L.

    2014-10-01

    In this paper, AA 2024 T3-rolled sheets were joined in butt joint configuration through the friction stir welding process. Different joints were carried out varying the principal process parameters (i.e., tool welding speed and tool rotational speed). The aim of this work was the study and the experimental characterization of the influence of the process parameters on the forces acting on the tool during the FSW process. Furthermore, it was studied the correlation between the forces and the grain size, in particular with the extension of the heat-affected zone. Forces acting along the axis parallel to the tool are actually greater than those acting along welding direction. All the recorded forces are strictly dependant on the process parameters adopted. No correlation has been found between the grain dimension within the weld bead and the recorded forces, while the greater the forces, the narrower the extension of the heat-affected zone.

  16. Effect of dust ion collision on dust ion acoustic waves in the framework of damped Zakharov-Kuznetsov equation in presence of external periodic force

    Science.gov (United States)

    Kanti Das, Tushar; Ali, Rustam; Chatterjee, Prasanta

    2017-10-01

    The dynamics of dust ion acoustic waves (DIAWs) is investigated in a magnetized dusty plasma whose constituents are cold ions, superthermal electrons, and dust particles in the framework of a damped Zakharov-Kuznetsov (dZK) equation in the presence of externally applied periodic force. The dZK equation is derived employing the standard reductive perturbation technique. The effect of dust ion collision on the quasiperiodic and chaotic motion of dust ion acoustic waves is discussed. It is observed that the collision frequency νid 0 plays the role of a switching parameter from the quasiperiodic route to chaos for the DIAWs.

  17. Tuning a PD Controller Based on an SVR for the Control of a Biped Robot Subject to External Forces and Slope Variation

    Directory of Open Access Journals (Sweden)

    João P. Ferreira

    2014-03-01

    The ZMP is calculated by reading four force sensors placed under each of the robot’s feet. The gait implemented in this biped is similar to a human gait, which is acquired and adapted to the robot’s size. The main contribution of this paper is the fine-tuning of the ZMP controller based on the SVR. To implement and test this, the biped robot was subjected to external forces and slope variation. Some experiments are presented and the results show that the implemented gait combined with the correct tuning of the SVR controller is appropriate for use with this biped robot. The SVR controller runs at 0.2 ms, which is about 50 times faster than a corresponding first- order TSK neural-fuzzy network.

  18. The application of an external wrist extension force reduces electromyographic activity of wrist extensor muscles during gripping.

    NARCIS (Netherlands)

    Elk, N. van; Faes, M.C.; Degens, H.; Kooloos, J.G.M.; Lint, J.A. de; Hopman, M.T.E.

    2004-01-01

    STUDY DESIGN: Experimental repeated-measures study. OBJECTIVE: To investigate the effect of different extension forces applied to the palm of the hand on electromyographic (EMG) activity of the wrist extensor muscles during hand gripping. BACKGROUND: Lateral epicondylitis is usually caused by repeti

  19. Application of DDA Approach to Simulation of Ice Breaking Process and Evaluation of Ice Force Acting on A Structure

    Institute of Scientific and Technical Information of China (English)

    张运良; 林皋; 李志军; 王永学

    2002-01-01

    The sea ice is idealized as an elastic-brittle material. When an ice sheet moves toward a structure, the dynamic in-teraction between ice and the structure is analyzed by the DDA (Discontinuous Deformation Analysis) approach, wherethe ice sheet and the structure are considered as assemblages of blocky masses. This has the advantages that the wholeprocess of collision between the ice and structure can be shown visually with a series of pictures. Meanwhile, the dynamicresponse of the structure at each time step after the bumping of the ice against the structure is calculated. And with theaid of inverse analysis developed by the authors, the time history of the resultant ice force exerting on the structure isevaluated. A numerical example shows that the proposed approach is suitable to the simulation of the ice-breaking processand reasonable result of ice force acting on the structure can be obtained.

  20. FORCEFUL ARRESTS: AN OVERVIEW OF SECTION 49 OF THE CRIMINAL PROCEDURE ACT 51 OF 1977 AND ITS RECENT AMENDMENTS

    Directory of Open Access Journals (Sweden)

    Rinda Botha

    2012-08-01

    Full Text Available The debate concerning the use of violence by the police force is an endless one. Section 49 of the Criminal Procedure Act 51 of 1977 serves as a framework for the use of violence by police officers during arrests in South Africa. While some hold the opinion that the powers of the police in this respect should be restricted, others see the 2003 redefined section 49 as a legislative guarantee of a suspect’s right to flee. Against this background this article has as its focus a critical discussion of the historical development of section 49 as well as the recent amendments of the same. The current legal position in South Africa is also compared with that in the United States of America as well as in the United Kingdom. Finally, certain conclusions and recommendations are made in order to enhance more favourable regulation of the employment of force in effecting arrests.

  1. Unsteady hydrodynamic forces acting on a robotic arm and its flow field: application to the crawl stroke.

    Science.gov (United States)

    Takagi, Hideki; Nakashima, Motomu; Ozaki, Takashi; Matsuuchi, Kazuo

    2014-04-11

    This study aims to clarify the mechanisms by which unsteady hydrodynamic forces act on the hand of a swimmer during a crawl stroke. Measurements were performed for a hand attached to a robotic arm with five degrees of freedom independently controlled by a computer. The computer was programmed so the hand and arm mimicked a human performing the stroke. We directly measured forces on the hand and pressure distributions around it at 200 Hz; flow fields underwater near the hand were obtained via 2D particle image velocimetry (PIV). The data revealed two mechanisms that generate unsteady forces during a crawl stroke. One is the unsteady lift force generated when hand movement changes direction during the stroke, leading to vortex shedding and bound vortex created around it. This bound vortex circulation results in a lift that contributes to the thrust. The other occurs when the hand moves linearly with a large angle of attack, creating a Kármán vortex street. This street alternatively sheds clockwise and counterclockwise vortices, resulting in a quasi-steady drag contributing to the thrust. We presume that professional swimmers benefit from both mechanisms. Further studies are necessary in which 3D flow fields are measured using a 3D PIV system and a human swimmer.

  2. Forces acting on a small particle in an acoustical field in a thermoviscous fluid

    CERN Document Server

    Karlsen, Jonas Tobias

    2015-01-01

    We present a theoretical analysis of the acoustic radiation force on a single small particle, either a thermoviscous fluid droplet or a thermoelastic solid particle, suspended in a viscous and heat-conducting fluid medium. Our analysis places no restrictions on the length scales of the viscous and thermal boundary layer thicknesses $\\delta_\\mathrm{s}$ and $\\delta_\\mathrm{t}$ relative to the particle radius $a$, but it assumes the particle to be small in comparison to the acoustic wavelength $\\lambda$. This is the limit relevant to scattering of sound and ultrasound waves from micrometer-sized particles. For particles of size comparable to or smaller than the boundary layers, the thermoviscous theory leads to profound consequences for the acoustic radiation force. Not only do we predict forces orders of magnitude larger than expected from ideal-fluid theory, but for certain relevant choices of materials, we also find a sign change in the acoustic radiation force on different-sized but otherwise identical parti...

  3. Forces acting on a small particle in an acoustical field in a viscous fluid

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Bruus, Henrik

    2012-01-01

    force, which is valid for any particle radius and boundary-layer thickness provided that both of these length scales are much smaller than the wavelength of the ultrasound wave (millimeters in water at megahertz frequencies). The acoustophoretic response of suspended microparticles is predicted...

  4. DYNAMIC MODEL OF CROP GROWTH SYSTEM AND NUMERICAL SIMULATION OF CROP GROWTH PROCESS UNDER THE MULTI-ENVIRONMENT EXTERNAL FORCE ACTION

    Institute of Scientific and Technical Information of China (English)

    李自珍; 王万雄; 徐彩琳

    2003-01-01

    According to the biomechanic theory and method, the dynamic mechanism of crop growth under the external force action of multi-environment factors (light, temperature, soil and nutrients etc.) was comprehensively explored. Continuous-time Markov (CTM) approach was adopted to build the dynamic model of the crop growth system and the simulated numerical method. The growth rate responses to the variation of the external force and the change of biomass saturation value were studied. The crop grew in the semiarid area was taken as an example to carry out the numerical simulation analysis, therefore the results provide the quantity basis for the field management. Comparing the dynamic model with the other plant growth model, the superiority of the former is that it displays multi-dimension of resource utilization by means of combining macroscopic with microcosmic and reveals the process of resource transition. The simulation method of crop growth system is advanced and manipulated. A real simulation result is well identical with field observational results.

  5. Numerical Calculation of the Drag Force Acting on a Solid Particle Pushed by a Solid/Liquid Interface

    Science.gov (United States)

    Catalina, Adrian V.; Stefanescu, Doru M.; Sen, Subhayu

    2000-01-01

    The distribution of insoluble particles in a metal casting depends primarily on the interaction of the particles with the solid/liquid interface (SLI) during the solidification process. The balance of the forces acting on the particle essentially determines whether a particle will be engulfed or pushed by the SLI. An important component of this force balance is the drag force generated by the particle motion in front of the SLI. Previously developed mathematical models for particle/SLI interaction made use of steady-state solutions of this force provided by the lubrication theory. However, our numerical model based on the SLI tracking approach shows that the steady-state approach is inappropriate to model the interaction process and that at steady-state the theoretical solution underestimates the drag force. It was found that regression analysis of steady-state numerical solutions for cylindrical particles moving normal to a flat SLI gives a relationship of the form: Abstract The distribution of insoluble particles in a metal casting depends primarily on the interaction of the particles with the solid/liquid interface (SLI) during the solidification process. The balance of the forces acting on the particle essentially determines whether a particle will be engulfed or pushed by the SLI. An important component of this force balance is the drag force generated by the particle motion in front of the SLI. Previously developed mathematical models for particle/SLI interaction made use of steady-state solutions of this force provided by the lubrication theory. However, our numerical model based on the SLI tracking approach shows that the steady-state approach is inappropriate to model the interaction process and that at steady-state the theoretical solution underestimates the drag force. It was found that regression analysis of steady-state numerical solutions for cylindrical particles moving normal to a flat SLI gives a relationship of the form: F(sub D, sup num) =sqoare

  6. About Radiation Reaction with Force Approach

    CERN Document Server

    Velazquez, Gustavo Lopez

    2015-01-01

    The difficulty of usual approach to radiation reaction is pointed out , and a possible approach based on the force acting to the charged particle which produces the acceleration itself, is presented. This approach brings about an expression such that acceleration is zero whenever the external force is zero.

  7. Priming Silicic Giant Magma Bodies: Finding Evidence for Internal Forcing Versus External Triggering of Supereruptions by Phase Equilibria Modeling.

    Science.gov (United States)

    Tramontano, S.; Gualda, G. A. R.; Ghiorso, M. S.; Kennedy, B.

    2015-12-01

    It is important to understand what triggers silicic eruptions because of the implications for modern-day systems. The goal of this project is to use phase equilibria modeling (i.e. rhyolite-MELTS) to determine to what extent magmas within the crust are induced to erupt due to external triggers (e.g. earthquakes; new magma injection; neighboring eruptions) and to what extent they naturally evolve to a point where eruption is inevitable (e.g. by fluid exsolution and decrease in magma strength and density). Whole-rock compositions from four rhyolite tuffs across the globe associated with large or supereruptions (Mamaku Tuff, New Zealand; Peach Spring Tuff, SW USA; early and late-erupted Bishop Tuff, California; and Toba Tuff, Indonesia) are studied using rhyolite-MELTS modeling. Key physical properties of magma are strongly affected by the initial volatile content due to fluid exsolution. By running simulations with varying water contents, we can track the evolution of fluid exsolution during crystallization. Isobaric (constrained temperature change at constant pressure) and isochoric (constrained temperature change at constant volume) models were run for the four compositions. In constrained-pressure scenarios, fluid is free to exsolve as crystallization proceeds, and the total system volume can increase or decrease accordingly; this would require deformation of the surrounding crust to accommodate the magma volume change. In constrained-volume scenarios, bubble exsolution is limited to the volume change due to crystallization; in this case, pressure can decrease or increase (if bubbles are absent or present). For fixed-pressure scenarios, fluid exsolution is more extensive and leads to internal triggering, at least for fluid-saturated conditions; external triggering is more likely in fluid-undersaturated conditions. For fixed-volume scenarios, none of the systems cross a fragmentation threshold for the crystal contents typically observed in natural pumice. If

  8. The Davis-Bacon Act: Cost Impact on the Air Force

    Science.gov (United States)

    1992-09-01

    June 1977 issue of the Labor Law Journal, Donald Elisburg, then Assistant Secretary of Labor for Employment Standards, discussed an Executive Order...1992). 7. Elisburg, Donald. "Wage Protection Under the Davis- Bacon Act," Labor Law Journal, 28: 323-328 (June 1977). 8. Federal Acquisition...R. "Davis-Bacon: Labor’s Anachronism 1974," Labor Law Journal, 25: 404-407 (July 1974). 59 Vita Raymond Carpenter was born on 18 August 1953 in

  9. “Coloniality of power” in East Central Europe: external penetration as internal force in post-socialist Hungarian politics

    Directory of Open Access Journals (Sweden)

    Agnes Gagyi

    2016-08-01

    Full Text Available Joining a series of analyses of effects of othering, orientalism, or coloniality in East Central Europe, the paper asks how long-term structural-ideological effects of global hierarchies, as reflected in post-colonial contexts by the term “coloniality of power,” can be conceptualized for East Central Europe. In a case study of political polarization in post-socialist Hungary,it examines the effects of global integration,  claiming that two dominant economic-political blocks formed along a division of vertical alliances related to integration with either Western or national capital. From those positions, they developed divergent political ideologies of development: modernization through Western integration, versus the protection of “national” wealth from Western capital and its local allies. While both propagated capitalist integration, they each needed to develop ideologies that appealed to electorates suffering the costs of integration. One framing of developmentalist emancipation promised Western modernity through rejection of popular, backward characteristics of the country, including nationalism. The other promised advancement in the global hierarchy through overcoming internal and external enemies of national development. These two, mutually reinforcing ideological positions, which I call“democratic antipopulism” and “antidemocratic populism,” denied the contradiction between elites’ and workers’ interest and perpetuated existing global hierarchies. Within the wider debate over cross-contextual applications of the notion of “coloniality of power,” and of emancipative efforts born from the “colonial wound,” the paper emphasizes the significance of the structural conditions, positions and alliances within which experiences of global domination are born and mobilized.

  10. Use of a device that applies external kneading-like force on the abdomen for treatment of constipation

    Institute of Scientific and Technical Information of China (English)

    Konstantinos Mimidis; David Galinsky; Efraim Rimon; Vassilios Papadopoulos; Yehuda Zicherman; Dimitrios Oreopoulos

    2005-01-01

    AIM: To evaluate the efficacy of a recently developed device that applies kneading-like motion on the abdomen in improving constipation in elderly long-term care patients.METHODS: Thirty constipated elderly patients were randomly selected from two nursing homes. They were instructed to use the device once daily for 20 min. Rate of bowel movements, volume and consistency of stool and the use of laxantia were all recorded during a 3-wk baseline period and for 12-wk treatment period. Colonic transit time (CTT) was measured in 13 patients by radiopaque markers during the baseline and at the end of treatment.RESULTS: Bowel movement rate (BM/week) increased from 1.4±0.4 BM/wk during baseline to 3.9±0.8 BM/wk during treatment (P<5.0×10-7). Stool amount that was "low" in 30 patients during baseline increased in 21 patients at the end of the study period (χ2 = 19.048-P =1.3×10-5). Stool consistency, that was "hard" in 25 patients and "soft" in 5 patients during baseline, ameliorated in 23 patients at the end of the study (only 2 patients referred "hard" stool) (χ2= 21.043-P = 4.0×10-6). The mean baseline CTT measured was 92.3±32.3 h at baseline and decreased to 49.4±31.3 h during the study period (P = 0.000208). No side effects were observed during the study period.CONCLUSION: External mechanical vibration of the abdomen reduced CTT and helped to relieve severe constipation in elderly constipated patients.

  11. AERODYNAMIC FORCES ACTING ON AN ALBATROSS FLYING ABOVE SEA-WAVES

    Institute of Scientific and Technical Information of China (English)

    SHENG Qi-hu; WU De-ming; ZHANG Liang

    2005-01-01

    Numerical investigation on the dynamic mechanism has been made for an albatross to fly effectively near sea surface. Emphasizing on the effect of the sea wave,the albatross is simplified as a two-dimensional airfoil and the panel method based on the potential flow theory is employed to calculate the wave effect on the aerodynamic forces. The numerical results have been presented for the states of flying at different constant speeds with constant heights above sea level, and flying at different constant speeds with the combined oscillations of pitching and free heaving. It is shown that the albatross flight efficiency depends on not only the speed and height of flight but also the wave amplitude and the wavelength. The albatross benefits by wave effect to get thrust,so as to reduce the resistance in the circumstances of rough sea.

  12. Quantum Statistics of a Forced Oscillator with a Time-Dependent Driving Force

    Institute of Scientific and Technical Information of China (English)

    刘文森

    2003-01-01

    Quantum statistics of a forced harmonic oscillator acted upon by a time-dependent external force are derived using the Wilcox trick and the time-dependent inhomogeneous Bogoliubov transformation formalism.The internal energy,fluctuation of the particle-number average and entropy of this nonequilibrium system are presented explicitly.

  13. Use of induced acceleration to quantify the (de)stabilization effect of external and internal forces on postural responses.

    Science.gov (United States)

    van Asseldonk, Edwin H F; Carpenter, Mark G; van der Helm, Frans C T; van der Kooij, Herman

    2007-12-01

    Due to the mechanical coupling between the body segments, it is impossible to see with the naked eye the causes of body movements and understand the interaction between movements of different body parts. The goal of this paper is to investigate the use of induced acceleration analysis to reveal the causes of body movements. We derive the analytical equations to calculate induced accelerations and evaluate its potential to study human postural responses to support-surface translations. We measured the kinematic and kinetic responses of a subject to sudden forward and backward translations of a moving platform. The kinematic and kinetics served as input to the induced acceleration analyses. The induced accelerations showed explicitly that the platform acceleration and deceleration contributed to the destabilization and restabilization of standing balance, respectively. Furthermore, the joint torques, coriolis and centrifugal forces caused by swinging of the arms, contributed positively to stabilization of the Center of Mass. It is concluded that induced acceleration analyses is a valuable tool in understanding balance responses to different kinds of perturbations and may help to identify the causes of movement in different pathologies.

  14. The role of integrated resource planning, environmental externalities, and anticipation of future regulation in compliance planning under the Clean Air Act Amendments of 1990

    Energy Technology Data Exchange (ETDEWEB)

    Bernow, S.; Biewald, B.; Wulfsberg, K. [Tellus Institute, Boston, MA (United States)

    1993-07-01

    Utilities are developing sulfur dioxide (SO{sub 2}) emission compliance plans to meet limitations of the Clean Air Act Amendments of 1990 (CAAA). Compliance plans will have long-term effects on resource selection, fuel choice, and system dispatch. Use of integrated resource planning (IRP) is necessary to ensure compliance plans are consistent with the overall societal goals. In particular, environmental externalities must be integrated with the compliance planning process. The focus of the CAAA is on air pollution reduction, specifically acid gases and toxics, and attainment of National Ambient Air Quality Standards (NAAQS) for criteria pollutants. Title IV specifically focuses on sulfur dioxide with a national allowance trading system, while further regulation of toxics and nitrogen oxides is slated for additional study. Yet, compliance planning based narrowly upon today`s environmental regulations could fail to meet the broad goals of IRP if a larger array of environmental externalities is excluded from the analysis. Compliance planning must consider a broad range of environmental effects from energy production and use to (1) protect society`s long-term stake in environmental quality, and (2) ensure that today`s plans are rich enough to accommodate potential changes in regulation and national environmental goals. The explicit recognition of environmental effects, such as those associated with CO{sub 2} release, will result in prudent compliance plans that take advantage of current opportunities for pollution avoidance and have long-term viability in the face of regulatory change. By including such considerations, the mix of resources acquired and operated (supply and demand, existing and new, conventional and renewable, fuel type and fuel quality, pollution control, and dispatch protocols) will be robust and truly least-cost.

  15. Effect of attractive interactions between polymers on the effective force acting between colloids immersed in a polymer system: Analytic liquid-state theory.

    Science.gov (United States)

    Chervanyov, A I

    2016-12-28

    By making use of the polymer reference interaction site model, we analytically study the effect of attractive interactions between polymers on the effective forces acting between colloids immersed in a polymer system. The performed theoretical analysis has no restrictions with respect to the polymer density and relative sizes of the colloids and polymers. The polymer mediated (PM) potential acting between colloids is shown to significantly depend on the strength and range of the polymer-polymer interactions. In the nano-particle limit, where the colloid radius is much smaller than the polymer gyration radius, the presence of attractive polymer-polymer interactions causes only quantitative changes to the PM potential. In the opposite limit of relatively large colloids, the polymer-polymer interactions revert the sign of the total effective force acting between colloids so that this force becomes attractive at sufficiently large polymer densities. With the objective to study an intricate interplay between the attractive PM forces and steric repulsion in different polymer density regimes, we calculate the second virial coefficient B of the total effective potential acting between colloids. The dependence of B on the polymer density is discussed in detail, revealing several novel features of the PM interactions caused by the presence of attractive polymer-polymer interactions.

  16. Effect of External Forced Flow and Boiling Film on Heat Transfer of AISI 4140 Steel Horizontal Rod During Direct Quenching%Effect of External Forced Flow and Boiling Film on Heat Transfer of AISI 4140 Steel Horizontal Rod During Direct Quenching

    Institute of Scientific and Technical Information of China (English)

    A H Meysami; R Ghasemzadeh; S H Seyedein; M R Aboutalebi

    2011-01-01

    The effects of rod falling and moving, external flow field, boiling film and radiation were investigated on fluid flow and heat transfer of AISI 4140 steel horizontal rod during direct quenching by mathematical modeling. The flow field and heat transfer in quenching tank were simulated by computational fluid dynamics (CFD) method considering falling and moving of rods during process. Therefore, modeling of flow field was done by a fixed-mesh method for general moving objects equations, and then, energy equation was solved with a numerical approach so that effeet of boiling film heat flux was considered as a source term in energy equation for solid-liquid boundary. Simulated results were verified by comparing with published and experimental data and there was a good agreement between them. Also, the effects of external forced flow and film boiling were investigated on heat flux output, temperature distribution and heat transfer coefficient of rod. Also simulated results determined optimum quenching time for this process.

  17. Seasonal and Interannual Fast-Ice Variability from MODIS Surface-Temperature Anomalies, and its Link to External Forcings in Atka Bay, Antarctica

    Science.gov (United States)

    Paul, S.; Hoppmann, M.; Willmes, S.; Heinemann, G.

    2016-12-01

    Around Antarctica, sea ice is regularly attached to coastal features. These regions of mostly seasonal fast ice interact with the atmosphere, ocean and coastal ecosystem in a variety of ways. The growth and breakup cycles may depend on different factors, such as water- and air temperatures, wind conditions, tides, ocean swell, the passage of icebergs and the presence of nearby polynyas. However, a detailed understanding about the interaction between these factors and the fast-ice cycle is missing. In order to better understand the linkages between general fast-ice evolution and external forcing factors, we present results from an observational case study performed on the seasonal fast-ice cover of Atka Bay, eastern Weddell Sea. The ice conditions in this region are critical for the supply of the German wintering station Neumayer III. Moreover, the fast ice at Atka Bay hosts a unique ecosystem based on the presence of a sub-ice platelet layer and a large emperor penguin colony. While some qualitative characterizations on the seasonal fast-ice cycle in this region exist, no proper quantification was carried out to date. The backbone of this work is a new algorithm, which yields the first continuous time series of open-water fractions from Moderate-Resolution Imaging Spectroradiometer (MODIS) surface temperatures. The open-water fractions are derived from a range of running multi-day median temperature composites, utilizing the thermal footprint of warm open water and thin ice in contrast to cold pack-ice/ice-shelf areas. This unique, and manually validated dataset allows us to monitor changes in fast-ice extent on a near daily basis, for a period of 14 years (2002-2015). In a second step, we combine these results with iceberg observations, data from the meteorological observatory, and auxiliary satellite data in order to identify the main factors governing fast-ice formation and break-up.

  18. Impact of external resistance and maximal effort on force-velocity characteristics of the knee extensors during strengthening exercise: a randomized controlled experiment.

    Science.gov (United States)

    Van Roie, Evelien; Bautmans, Ivan; Boonen, Steven; Coudyzer, Walter; Kennis, Eva; Delecluse, Christophe

    2013-04-01

    It remains controversial whether maximal effort attained by high external resistance is required to optimize muscle adaptation to strengthening exercise. Here, we compared different training protocols reaching maximal effort with either high-resistance (HImax, 80% of 1-repetition maximum [1RM]) or low-resistance (LOmax, ≤40% 1RM). Thirty-six young volunteers were randomly assigned to 9 weeks of leg extension training at either HImax (1 set of 10-12 repetitions at 80% 1RM), LO (1 set of 10-12 repetitions at 40% 1RM, no maximal effort), or LOmax (1 set of 10-12 repetitions at 40% 1RM, preceded [no rest] by 60 repetitions at 20-25% 1RM). Knee extension 1RM was measured preintervention and postintervention and before the 7th, 13th, and 19th training sessions. Preintervention and postintervention, knee extensor static (PTstat) and dynamic (PTdyn) peak torque, maximal work (MW), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat were recorded with a Biodex dynamometer. All the groups showed a significant increase in 1RM, with a greater improvement in HImax from the 13th session on (p < 0.05). The HImax was the only group that significantly increased PTstat (+7.4 ± 8.1%, p = 0.01). The LOmax showed a significantly greater increase in S20 (+6.0 ± 3.2%), PTdyn (+9.8 ± 5.6%), and MW (+15.1 ± 10.6%) than both HImax and LO (p = 0.044 for S20, p = 0.030 for PTdyn, p = 0.025 for MW) and was the only group that increased in S40 (+7.7 ± 9.7%, p = 0.032). In conclusion, significant differences between HImax and LOmax on force-velocity characteristics of the knee extensors were found, although maximal effort was achieved in both training regimens. Thus, LOmax may not be considered as a replacement for HImax but rather as an alternative with different training-specific adaptations.

  19. The main features of seasonal variability in the external forcing and dynamics of a deep mountain lake (Redó, Pyrenees

    Directory of Open Access Journals (Sweden)

    David M. LIVINGSTONE

    2000-09-01

    Full Text Available Lake Redó, a dimictic oligotrophic mountain lake, was monitored for two complete years from July 1996 to July 1998. The main seasonal variations in the physical, chemical and biological parameters are described, with special emphasis on the comparison of external forcing (weather and atmospheric deposition with internal lake dynamics. Annual mean air temperature was estimated to be 3.6 °C. The duration of ice cover on the lake was 4.5 months in 1996/97 and 5.8 months in 1997/98. The lake water was very ionpoor (mean annual conductivity 12 μS cm-1; however, ion concentrations in the lake were higher than in the precipitation, the differences being due mainly to Ca2+ and bicarbonates originating in the catchment. NH4 + was the main ion in the precipitation, with an average concentration of 17 μM, while in the lake it was always below 3 μM. However, the concentration of dissolved inorganic nitrogen always exceeded that of soluble reactive phosphorus by two or three orders of magnitude, so the latter is likely to be the limiting nutrient for phytoplankton growth. Four main production episodes were identified, occurring during spring and autumn overturn, in the upper hypolimnion during summer stratification, and under the ice at the beginning of the ice-covered period. The highest chlorophyll-a concentrations (1.2-2.2 μg l-1 were attained during spring overturn; concentrations of chlorophyll-c were high during both spring and autumn overturn, while chlorophyll-b was comparatively important in the upper hypolimnion during the stratification period. Daphnia pulicaria was the most abundant macrozooplankton species; its abundance was highest during the icecovered period, when its biomass was comparable to the measured sestonic particulate carbon concentration. The Daphnia maximum was associated with higher concentrations of NH4 + and dissolved organic carbon, suggesting that it may play an important role in the pelagic biogeochemical compartment of

  20. The rotational barrier of ethane and some of its hexasubstituted derivatives in terms of the forces acting on the electron distribution.

    Science.gov (United States)

    Cortés-Guzmán, Fernando; Cuevas, Gabriel; Martín Pendás, Ángel; Hernández-Trujillo, Jesús

    2015-07-15

    A novel and alternative explanation of the rotational barrier of ethane and several hexasubstituted derivatives, CX3CX3 (X = H, F, CH3, Cl, Br), is suggested based on the evaluation of the properties of the electron distribution. The forces exerted on the electron density of the topological atoms making up a molecule, the Ehrenfest forces, are analyzed and, with the help of the virial theorem, they are used to explain the experimental rotational barriers. According to this approach, the barrier is mainly a consequence of the decrease of the always attractive Ehrenfest forces (EFs) linking the two C atoms. In addition, the behavior of the EFs is related to a decrease of stability of the central C atoms, which is not compensated by the stabilization of the substituents. Also, during rotation from the staggered to the equilibrium conformation, the electron density at the C-C bond critical point and the electron delocalization between C atoms decrease and are accompanied by an increase of electron delocalization between the substituents. According to the analysis of the EF field lines and to the behavior of the integrated forces, the rotational barrier cannot be explained as a result of any repulsive forces acting on the electron density, although a possible interpretation of the quantum force that balances the EF in stationary states as a measure of traditional Pauli repulsions is also examined.

  1. RPTP-alpha acts as a transducer of mechanical force on alphav/beta3-integrin-cytoskeleton linkages

    DEFF Research Database (Denmark)

    von Wichert, Gotz; Jiang, Guoying; Kostic, Ana

    2003-01-01

    Cell motility on ECM critically depends on the cellular response to force from the matrix. We find that force-dependent reinforcement of alphav/beta3-integrin-mediated cell-matrix connections requires the receptor-like tyrosine phosphatase alpha (RPTPalpha). RPTPalpha colocalizes with alphav-inte...

  2. Analytical model for viscous damping and the spring force for perforated planar microstructures acting at both audible and ultrasonic frequencies

    Science.gov (United States)

    Homentcovschi, Dorel; Miles, Ronald N.

    2008-01-01

    The paper presents a model for the squeezed film damping, the resistance of the holes, and the corresponding spring forces for a periodic perforated microstructure including the effects of compressibility, inertia, and rarefied gas. The viscous damping and spring forces are obtained by using the continuity equation. The analytical formula for the squeezed film damping is applied to analyze the response of an ultrasonic transducer. The inclusion of these effects in a model significantly improves the agreement with measured results. Finally, it is shown that the frequency dependence of the total damping and total spring force for a cell are very similar to those corresponding to a rectangular open microstructure without holes. A separate analysis reveals the importance of each particular correction. The most important is the compressibility correction; the inertia has to be considered only for determining the spring force and the damping force for sufficiently high frequencies. PMID:18646964

  3. Mammography Screening in a Large Health System Following the U.S. Preventive Services Task Force Recommendations and the Affordable Care Act.

    Science.gov (United States)

    Nelson, Heidi D; Weerasinghe, Roshanthi; Wang, Lian; Grunkemeier, Gary

    2015-01-01

    Practice recommendations for mammography screening were issued by the U.S. Preventive Services Task Force in 2009 and expansion of insurance coverage was provided under the Patient Protection and Affordable Care Act soon thereafter, yet the influence of these changes on screening practices in the United States is not known. To determine changes in mammography screening and their associations with new practice recommendations and the Affordable Care Act, we examined patient-level data from 249,803 screening mammograms from January 1, 2008 through December 31, 2012 in a large community-based health system in the northwestern United States. Associations were determined by an intervention analysis of time-series data method. Among women screened, 64% were age 50-74 years; 84% self-identified as white race; 62% had commercial insurance; and 70% were seen in facilities located in metropolitan areas. Practice recommendations were associated with decreased screening volumes among women age Act was associated with increased screening among women age 50-74 (+184.3 mammograms/month; +7.2% change; P=0.001), but not women Act was associated with increased screening for women with Medicare, Medicaid, or other noncommercial sources of payment. Mammography screening volumes in a large community health system decreased among women age Act were associated with increased screening volumes among women age 50-74.

  4. American Recovery and Reinvestment Act (ARRA) Federal Energy Management Program Technical Assistance Project 224 Altus Air Force Base Solar Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Bryan J.

    2010-09-30

    The principal goal of this project was to evaluate altus Air Force Base for building integrated silicon or thin film module photovoltaic opportunities. This report documents PNNL's efforts and documents study conclusions.

  5. Construction robot force control in cleaning operations

    Science.gov (United States)

    Zhou, Y.; Skibniewski, M. J.

    1994-01-01

    Basic surface treatment tasks on construction sites that can be performed by robots include the spraying, cleaning, and finishing of surfaces. In the present paper, a construction robot is proposed for accomplishing a variety of cleaning tasks in construction. Specifically, the force-control problem in cleaning a surface is studied. The paper shows that a force sensor can be used not only to monitor the force acting at the contact points, but also to identify the uncertainties of the unstructured construction environment. A different formulation for the external force is presented. With this formulation, the external force on the end-effector is presented as a function of the contact force, contact torque, and constraint conditions, but not the actuated torque in the joint space. Therefore, the force-control problem is simplified to compensate for the external force and to exert a desired force. One advantage fo this approach is that the original PID position control loop of an industrial robot is retained so that the time-consuming computed torque method is avoided. The proposed control scheme can be applied to numerous cleaning tasks with hard contact regardless of the different nature of the surface.

  6. 基于BP神经网络的体外索索力预测及MATLAB实现%Prediction of the external tendons force based on BP neural network and MATLAB

    Institute of Scientific and Technical Information of China (English)

    熊辉霞; 张耀庭; 苗雨

    2011-01-01

    为了进一步研究体外预应力混凝土结构体外索极限应力的确定方法,在分析影响体外预应力混凝土结构体外索极限应力因素的基础上,运用神经网络预测的原理,采用误差反向传播神经网络即BP神经网络对体外索的索力进行了预测.预测结果表明,应用BP神经网络模型能准确的预测体外索的索力.预测结果和试验结果相比误差在10%以内,可以满足实际工程的需要.%In order to determine the maximum stress of the externally prestressed concrete structures, various factors that influence the stress were analyzed, and the theory of BP (Back Propagation) neural network was used to predict the external tendon force. The results show that the BP neural network model can predict the limit of the external tendon force and the error of the results is less than 10% compared to the experiment results, which is good enough to satisfy practical engineering needs.

  7. Fast and accurate prediction for aerodynamic forces and moments acting on satellites flying in Low-Earth Orbit

    Science.gov (United States)

    Jin, Xuhon; Huang, Fei; Hu, Pengju; Cheng, Xiaoli

    2016-11-01

    A fundamental prerequisite for satellites operating in a Low Earth Orbit (LEO) is the availability of fast and accurate prediction of non-gravitational aerodynamic forces, which is characterised by the free molecular flow regime. However, conventional computational methods like the analytical integral method and direct simulation Monte Carlo (DSMC) technique are found failing to deal with flow shadowing and multiple reflections or computationally expensive. This work develops a general computer program for the accurate calculation of aerodynamic forces in the free molecular flow regime using the test particle Monte Carlo (TPMC) method, and non-gravitational aerodynamic forces actiong on the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite is calculated for different freestream conditions and gas-surface interaction models by the computer program.

  8. Identification of the nonlinear excitation force acting on a bowed string using the dynamical responses at remote locations

    Energy Technology Data Exchange (ETDEWEB)

    Debut, V.; Antunes, J. [ITN, ADL, P-2686 Sacavem Codex (Portugal); Delaune, X. [CEA Saclay, DEN, DM2S, SEMT, Lab Etud Dynam, F-01101 Gif Sur Yvette (France)

    2010-07-01

    For achieving realistic numerical simulations of bowed string instruments, based on physical modeling, a good understanding of the actual friction interaction phenomena is of great importance. Most work published in the field including our own has assumed that bow/string frictional forces behave according to the classical Coulomb stick-slip model, with an empirical velocity-dependent sliding friction coefficient. Indeed, the basic self-excited string motions (such as the Helmholtz regime) are well captured using such friction model. However, recent work has shown that the tribological behavior of the bow/string rosin interface is rather complex, therefore the basic velocity-dependent Coulomb model may be an over-simplistic representation of the friction force. More specifically, it was suggested that a more accurate model of the interaction force can be achieved by coupling the system dynamical equations with a thermal model which encapsulates the complex interface phenomena. In spite of the interesting work performed by Askenfelt, a direct measurement of the actual dynamical friction forces without disturbing the string motion is quite difficult. Therefore, in this work we develop a modal-based identification technique making use of inverse methods and optimization techniques, which enables the identification of the interface force, as well as the string self-excited motion, from the dynamical reactions measured at the string end supports. The method gives convincing results using simulated data originated from nonlinear computations of a bowed string. Furthermore, in cases where the force identifications are very sensitive to errors in the transfer function modal parameters, we suggest a method to improve the modal frequencies used for the identifications. Preliminary experimental results obtained using a basic bowing device, by which the string is excited with the stick of the bow, are then presented. Our identifications, from the two dynamical string reactions

  9. LIGHT PRESSURE: Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    Science.gov (United States)

    Guzatov, D. V.; Gaida, L. S.; Afanas'ev, Anatolii A.

    2008-12-01

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves.

  10. Aberrant Force Processing in Schizophrenia.

    Science.gov (United States)

    Martinelli, Cristina; Rigoli, Francesco; Shergill, Sukhwinder S

    2016-07-06

    Initially considered as mere side effects of antipsychotic medication, there is now evidence that motor and somatosensory disturbances precede the onset of the illness and can be found in drug-naive patients. However, research on the topic is scarce. Here, we were interested in assessing the accuracy of the neural signal in detecting parametric variations of force linked to a voluntary motor act and a received tactile sensation, either self-generated or externally generated. Patients with a diagnosis of schizophrenia and healthy controls underwent functional magnetic resonance imaging while asked to press, or abstain from pressing, a lever in order to match a visual target force. Forces, exerted and received, varied on 10 levels from 0.5 N to 5 N in 0.5 N increments. Healthy participants revealed a positive correlation between force and activity in contralateral primary somatosensory area (S1) when performing a movement as well as when receiving a tactile sensation but only when this was externally, and not self-, generated. Patients showed evidence of altered force signaling in both motor and tactile conditions, as well as increased correlation with force when tactile sensation was self-generated. Findings are interpreted in line with accounts of predictive and sensory integration mechanisms and point toward alterations in the encoding of parametric forces in the motor and somatosensory domain in patients affected by schizophrenia.

  11. Facial expressions and speech acts: experimental evidences on the role of the upper face as an illocutionary force indicating device in language comprehension.

    Science.gov (United States)

    Domaneschi, Filippo; Passarelli, Marcello; Chiorri, Carlo

    2017-08-01

    Language scientists have broadly addressed the problem of explaining how language users recognize the kind of speech act performed by a speaker uttering a sentence in a particular context. They have done so by investigating the role played by the illocutionary force indicating devices (IFIDs), i.e., all linguistic elements that indicate the illocutionary force of an utterance. The present work takes a first step in the direction of an experimental investigation of non-verbal IFIDs because it investigates the role played by facial expressions and, in particular, of upper-face action units (AUs) in the comprehension of three basic types of illocutionary force: assertions, questions, and orders. The results from a pilot experiment on production and two comprehension experiments showed that (1) certain upper-face AUs seem to constitute non-verbal signals that contribute to the understanding of the illocutionary force of questions and orders; (2) assertions are not expected to be marked by any upper-face AU; (3) some upper-face AUs can be associated, with different degrees of compatibility, with both questions and orders.

  12. Estimation of the forces acting on the tibiofemoral joint during knee extension exercises performed on an open kinetic chain strength-training machine

    Directory of Open Access Journals (Sweden)

    Jefferson Fagundes Loss

    2008-01-01

    Full Text Available The objectives of this study were to: (1 evaluate the resistive torque of an open kinetic chain strength-training machine for performing knee extensions, and (2 perform an analysis estimating internal forces in the tibiofemoral joint. During a fi rst phase of the study, measurements were taken of the machine under analysis (external forces, and then calculations were performed to estimate forces on the lower limb (internal forces. Equations were defi ned to calculate human force (HF, and the moment of muscular force (MMF. Perpendicular muscular force (MFp and joint force (JFp, axial muscular force (MF” and joint force (JF”, and total muscular force (MF and joint force (JF were all calculated. Five knee angles were analyzed (zero, 30, 45, 60, and 90 degrees. A reduction was observed in HF at higher knee angles, while MF and JF also increased at the same time. HF was always lower than the load selected on the machine, which indicates a reduced overload imposed by the machine. The reduction observed in MFp and JFp at higher knee angles indicates a lower tendency to shear the tibia in relation to the femur. At the same time, there was an increase in JF” due to higher MF”. The biomechanical model proposed in this study has shown itself adequate for the day-to-day needs of professionals who supervise orient strength training. resumo Os objetivos do presente estudo foram: (1 avaliar o torque de resistência (TR de uma máquina de musculação para a realização do exercício de extensão dos joelhos em cadeia cinética aberta e (2 realizar um ensaio teórico a partir do comportamento do TR com o intuito de estimar as forças internas na articulação tíbio-femoral. O estudo foi realizado em dois momentos: (1 medições da máquina utilizada e (2 estimativa das forças externas (na máquina e internas (no membro inferior. Foram utilizadas equações baseadas em um modelo mecânico bi-dimensional para o cálculo das componentes perpendiculares

  13. The centrally acting non-narcotic antitussive tipepidine produces antidepressant-like effect in the forced swimming test in rats.

    Science.gov (United States)

    Kawaura, Kazuaki; Ogata, Yukino; Inoue, Masako; Honda, Sokichi; Soeda, Fumio; Shirasaki, Tetsuya; Takahama, Kazuo

    2009-12-14

    The antidepressant-like effect of tipepidine was studied in rats. Tipepidine at 20 and 40 mg/kg i.p. reduced immobility in the forced swimming test and tipepidine at 40 mg/kg, i.p. increased climbing in the test. The drug at 40 mg/kg, i.p. had no effect on the locomotor activity and motor coordination. These results suggest that tipepidine may be a novel drug with antidepressant-like activity.

  14. 3D-modeling for determination of axial forces acting in elements of the end zone of power turbogenerators

    Directory of Open Access Journals (Sweden)

    Y.A.Haydenko

    2013-12-01

    Full Text Available A field mathematical model of the end zone of a powerful generator type TVV-1000-2U3 in the 3D-setting is developed. Modelling of the nominal mode of turbogenerator operation is done. The distribution of the electromagnetic field, eddy currents, and the Ampere force appearing in such elements of the end zone of turbogenerator as the pressure plate, push pins and electrically conductive screen.

  15. Relative contributions of external SST forcing and internal atmospheric variability to July-August heat waves over the Yangtze River valley

    Science.gov (United States)

    Chen, Xiaolong; Zhou, Tianjun

    2017-08-01

    The Yangtze River valley (YRV), located in central-eastern China, has witnessed increased numbers of heat waves in the summer since 1951. Knowing what factors control and affect the interannual variability of heat waves, especially distinguishing the contributions of anomalous sea surface temperature (SST) forcings and those of internal modes of variability, is important to improving heat wave prediction. After evaluating 70 members of the atmospheric model intercomparison project (AMIP) experiments from the 25 models that participated in the coupled model intercomparison project phase 5 (CMIP5), 13 high-skill members (HSMs) are selected to estimate the SST-forced variability. The results show that approximately 2/3 of the total variability of the July-August heat waves in the YRV during 1979-2008 can be attributed to anomalous SST forcings, whereas the other 1/3 are due to internal variability. Within the SST-forced component, one-half of the influence is from the impact of the El Niño-Southern Oscillation (ENSO) and the other half is from non-ENSO related SST forcings, specifically, the SST anomalies in the North Pacific and the North Atlantic. Both the decaying El Niño and developing La Niña accompanied by a warm Indian Ocean and cold central Pacific, respectively, are favorable to hotter summers in the YRV because these patterns strengthen and extend the western North Pacific Subtropical High (WNPSH) westwards, for which the decaying ENSO plays a dominant role. The internal variability shows a circumglobal teleconnection in which Rossby waves propagate southeastwards over the Eurasian Continent and strengthen the WNPSH. Atmospheric model sensitivity experiments confirm that non-ENSO SST forcings can modulate the WNPSH and heat wave variability by projecting their influences onto the internal mode.

  16. Medição precisa das forças de aceleração em cabos Precise measurement of acceleration forces acting on cables

    Directory of Open Access Journals (Sweden)

    Edgar Moraes do Nascimento

    1986-10-01

    Full Text Available Certos problemas do uso do cinto de segurança ainda não foram resolvidos, sendo importante a determinação precisa das forças nos cabos. Existem vários métodos que, da maneira que são aplicados, são de pouca precisão. Com o objetivo de suspender essa imprecisão são apresentados três métodos e aperfeiçoado um outro de determinação da força exercida no cabo. Um desses métodos aplica-se a países subdesenvolvidos.Certain problems related to the use of safety belts remain unsolved, important among them being the exact determination of forces acting on cables. Various methods of calculation, severely limited because of the way in which they are applied, are presented. Three methods with a view to surpassing these limits are presented and another for the calculation of the forces acting on a cable is perfected. One of these methods is applicable in developing countries.

  17. Office of Inspector General report on audit of work force restructuring under Section 3161 of the National Defense Authorization Act

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-05-01

    As authorized by the National Defense Authorization Act for Fiscal year 1993, Department of Energy (Department) policy is to provide educational assistance to terminated contractor employees who were impacted by the Department`s downsizing. A terminated employee is anyone who voluntarily or involuntarily departs due to a reduction in employment under a Departmental restructuring plan. The objectives of the audit were to determine if the Department provided (1) reasonable means for terminated contractor employees to obtain training to qualify for new employment and (2) reasonable compensation to southern Nevada for any impact the Department`s downsizing had on the community.

  18. On the estimation method of hydrodynamic forces acting on a huge floating structure; Choogata futai ni hataraku haryoku ryutairyoku no suiteiho ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kagemoto, H.; Fujino, M.; Zhu, T. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    A floating structure such as an international airport is anticipated to have a length of about 5,000 m and a width of about 1,000 m. A singular point method may be used as a method to estimate force that such a floating body is subjected to from waves. In order to derive a solution with practically sufficient accuracy, 1250 elements are required in the length direction and 250 elements in the width direction, or a total of 312,500 elements. Calculating this number of elements should use finally a linear equation system handling complex coefficients comprising 312,500 elements, which would require a huge amount of calculation time. This paper proposes a method to derive solution on wave forces acting on a super-large floating structure or fluid force coefficients such as added mass coefficients and decay coefficients at a practically workable calculation amount and still without degrading the accuracy. The structure was assumed to be a box-shaped structure. Strengths of the singular points to be distributed on each element were assumed to be almost constant except for edges in lateral, oblique and longitudinal waves. Under this assumption, the interior of the floating structure excepting its edges was represented by several large elements to have reduced the number of elements. A calculation method proposed based on this conception was verified of its effectiveness. 2 refs., 25 figs., 3 tabs.

  19. DLVO, hydrophobic, capillary and hydrodynamic forces acting on bacteria at solid-air-water interfaces: Their relative impact on bacteria deposition mechanisms in unsaturated porous media.

    Science.gov (United States)

    Bai, Hongjuan; Cochet, Nelly; Pauss, André; Lamy, Edvina

    2017-02-01

    Experimental and modeling studies were performed to investigate bacteria deposition behavior in unsaturated porous media. The coupled effect of different forces, acting on bacteria at solid-air-water interfaces and their relative importance on bacteria deposition mechanisms was explored by calculating Derjaguin-Landau-Verwey-Overbeek (DLVO) and non-DLVO interactions such as hydrophobic, capillary and hydrodynamic forces. Negatively charged non-motile bacteria and quartz sands were used in packed column experiments. The breakthrough curves and retention profiles of bacteria were simulated using the modified Mobile-IMmobile (MIM) model, to identify physico-chemical attachment or physical straining mechanisms involved in bacteria retention. These results indicated that both mechanisms might occur in both sand. However, the attachment was found to be a reversible process, because attachment coefficients were similar to those of detachment. DLVO calculations supported these results: the primary minimum did not exist, suggesting no permanent retention of bacteria to solid-water and air-water interfaces. Calculated hydrodynamic and resisting torques predicted that bacteria detachment in the secondary minimum might occur. The capillary potential energy was greater than DLVO, hydrophobic and hydrodynamic potential energies, suggesting that film straining by capillary forces might largely govern bacteria deposition under unsaturated conditions.

  20. Legal Assessment of the Legal Force Exclusion of the 1st Prudential Procedure in the Act on Public Finance

    Directory of Open Access Journals (Sweden)

    Marcin Tyniewicki

    2014-03-01

    Full Text Available By the amendment of the Act on Public Finance of 26 July 2013, Polish legislature made a temporary suspension – till the end of 2013 – of the application of the provisions governing the Ist prudential procedure. This procedure has a crucial meaning for reducing the growth of budget deficit and in consequence – reducing public debt growth. In case of such crucial provisions for public finance, any amendments should be carried out in situations really justified and exceptional as well as with careful respecting of principles of proper legislation. In these aspects mentioned amendment rises a number of objections. For example, rapid pace of parliamentary works causes doubts about correctness of the legislative process. Therefore, in this article the author tries to make a legal assessment of the amendment of the Act on Public Finance of 26 July 2013, both from the formal and legal point of view and taking into the consideration the importance of provisions governing the prudential procedure for whole sphere of Polish public finance.

  1. A New Model Potential Acting on the Excited Electron Within Molecules:Application to Calculate the Recurrence Spectra of Excited H2 Molecules in Strong External Fields

    Institute of Scientific and Technical Information of China (English)

    WANG De-Hua; DING Shi-Liang

    2004-01-01

    By using the molecular orbit theory, we give a new model potential acting on the excited electron within a molecule. The potential is the total interaction energy of this electron with all the nuclei and other electrons.We find that the introduction of a new model potential results in an extreme increase of the number of closed orbits as compared to the hydrogen atom. Making use of the molecular closed-orbit theory (MCOT) and the new model potential, we calculate the recurrence spectra of H2 molecules in parallel electric and magnetic fields for different quantum defects. The modulations in the spectra can be analysed in terms of the scattering of the excited electron on the molecular core. Our results are in good agreement with the quantum results.

  2. Experimental Study on the Impact of External Geometrical Shape on Free and Forced Convection Time Dependent Average Heat Transfer Coefficient during Cooling Process

    Directory of Open Access Journals (Sweden)

    Sundus Hussein Abd

    2012-01-01

    Full Text Available In this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. The impact of changing the body location within the air duct and the air speed are also demonstrated. The cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. Each cylinder was heated to a certain temperature and put inside the duct at certain locations. The temperature of the cylinder was then monitored. The heat transfer coefficient were then calculated for forced convection for several Reynolds number (4555-18222.The study covered free convection impact for values of Rayleigh number ranging between (1069-3321. Imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. These imperical equations were found to be in good comparison with that of other sources.

  3. Families of Fokker-Planck equations and the associated entropic form for a distinct steady-state probability distribution with a known external force field.

    Science.gov (United States)

    Asgarani, Somayeh

    2015-02-01

    A method of finding entropic form for a given stationary probability distribution and specified potential field is discussed, using the steady-state Fokker-Planck equation. As examples, starting with the Boltzmann and Tsallis distribution and knowing the force field, we obtain the Boltzmann-Gibbs and Tsallis entropies. Also, the associated entropy for the gamma probability distribution is found, which seems to be in the form of the gamma function. Moreover, the related Fokker-Planck equations are given for the Boltzmann, Tsallis, and gamma probability distributions.

  4. Molecular dynamics study of force acting on a model nano particle immersed in fluid with temperature gradient: Effect of interaction potential

    Science.gov (United States)

    Tsuji, Tetsuro; Iseki, Hirotaka; Hanasaki, Itsuo; Kawano, Satoyuki

    2016-11-01

    Thermophoresis of a nano particle in a fluid is investigated using molecular dynamics simulation. In order to elucidate effective factors on the characteristics of thermophoresis, simple models for both the fluid and the nano particle are considered, namely, the surrounding fluid consists of Lennard-Jones (LJ) particles and the model nano particle is a cluster consisting of several tens of LJ particles. Interaction between the fluid particle and the model nano particle is described by the LJ interaction potential or repulsive interaction potential with the Lorentz-Berthelot mixing rule. As a preliminary result, the effect of mass on thermophoretic force acting on the model nano particle is investigated for both interaction potentials.

  5. Toward an Engineering Model for the Aerodynamic Forces Acting on Wind Turbine Blades in Quasisteady Standstill and Blade Installation Situations

    Science.gov (United States)

    Gaunaa, Mac; Heinz, Joachim; Skrzypiński, Witold

    2016-09-01

    The crossflow principle is one of the key elements used in engineering models for prediction of the aerodynamic loads on wind turbine blades in standstill or blade installation situations, where the flow direction relative to the wind turbine blade has a component in the direction of the blade span direction. In the present work, the performance of the crossflow principle is assessed on the DTU 10MW reference blade using extensive 3D CFD calculations. Analysis of the computational results shows that there is only a relatively narrow region in which the crossflow principle describes the aerodynamic loading well. In some conditions the deviation of the predicted loadings can be quite significant, having a large influence on for instance the integral aerodynamic moments around the blade centre of mass; which is very important for single blade installation applications. The main features of these deviations, however, have a systematic behaviour on all force components, which in this paper is employed to formulate the first version of an engineering correction method to the crossflow principle applicable for wind turbine blades. The new correction model improves the agreement with CFD results for the key aerodynamic loads in crossflow situations. The general validity of this model for other blade shapes should be investigated in subsequent works.

  6. Centripetal Acceleration and Centrifugal Force in General Relativity

    Science.gov (United States)

    Bini, D.; de Felice, F.; Jantzen, R. T.

    2003-05-01

    In nonrelativistic mechanics noninertial observers studying accelerated test particle motion experience a centripetal acceleration which, once interpreted as a centrifugal force acting on the particle, allows writing the particle's equation of motion in a Newtonian form, simply by adding the inertial force contribution to that of the external forces in the acceleration-equals-force equation. In general relativity centripetal and centrifugal acceleration generalizing the classical concepts must be properly (geometrically) defined. This requires a relative Frenet-Serret frame approach based on a family of test observers.

  7. Assessing the industry using Porter's five forces.

    Science.gov (United States)

    2014-01-01

    To develop a business and plan for the future, there is a need to assess the current situation. One way of doing this is to use Porter's five forces framework. This was the brainchild of Harvard Business School's Michael Porter and developed in 1979. Looking at the competitive intensity of an industry, the model assesses internal and external factors that act together to determine the direction of the business; taken together, this gives an indication of the attractiveness of the industry.

  8. Study on estimating fluid force acting on a hull during maneuvering movement; Soju undoji no sentai ni sayosuru ryutairyoku no suitei ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Yukawa, K.; Kijima, K. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1997-10-01

    With types of general cargo vessel and VLCC vessel as the object of discussion, a method was discussed to estimate fluid force acting theoretically on a hull during maneuvering movement, taking frame line shape into consideration. A vortex model was improved by giving consideration of time-based decay on intensity of discrete vortex lines based on the Rankine vortex. Modeling of flow fields around a hull was attempted to deal with movements in which width and draft are small as compared with the ship length, and turning angle speed and deviation angle are small. It was assumed that the ship speed is slow and effects of waves can be disregarded. Specular images of the hull were taken with regard to free surface, and handled as a double body model. Speed potential to express flow fields around a hull is required to satisfy the following five boundary conditions of Laplace, substance surface, free vortex layers, infinity and exfoliation. The potential may be handled as a two-dimensional problem in a field near the hull by using assumption of a slender and long body and conformal mapping. It was found possible to estimate hull fluid force with relatively good accuracy. Fine linear coefficients derived from the estimation were used to have performed highly accurate determination on course stabilization. 5 refs., 6 figs., 2 tabs.

  9. Effect of melt convection at various gravity levels and orientations on the forces acting on a large spherical particle in the vicinity of a solidification interface

    Science.gov (United States)

    Bune, Andris V.; Sen, Subhayu; Mukherjee, Sundeep; Catalina, Adrian; Stefanescu, Doru M.

    2000-04-01

    Numerical modeling was undertaken to analyze the influence of both radial and axial thermal gradients on convection patterns and velocities during solidification of pure Al and an Al-4 wt% Cu alloy. The objective of the numerical task was to predict the influence of convective velocity on an insoluble particle near a solid/liquid (s/l) interface. These predictions were then be used to define the minimum gravity level ( g) required to investigate the fundamental physics of interactions between a particle and a s/l interface. This is an ongoing NASA funded flight experiment entitled "particle engulfment and pushing by solidifying interfaces (PEP)". Steady-state calculations were performed for different gravity levels and orientations with respect to the gravity vector. The furnace configuration used in this analysis is the quench module insert (QMI-1) proposed for the Material Science Research Facility (MSRF) on board the International Space Station (ISS). The general model of binary alloy solidification was based on the finite element code FIDAP. At a low g level of 10 -4g 0 ( g 0=9.8 m/s 2) maximum melt convection was obtained for an orientation of 90°. Calculations showed that even for this worst case orientation the dominant forces acting on the particle are the fundamental drag and interfacial forces.

  10. Biogeochemistry and ecosystems of continental margins in the western North Pacific Ocean and their interactions and responses to external forcing - an overview and synthesis

    Science.gov (United States)

    Liu, K.-K.; Kang, C.-K.; Kobari, T.; Liu, H.; Rabouille, C.; Fennel, K.

    2014-12-01

    In this special issue we examine the biogeochemical conditions and marine ecosystems in the major marginal seas of the western North Pacific Ocean, namely, the East China Sea, the Japan/East Sea to its north and the South China Sea to its south. They are all subject to strong climate forcing as well as anthropogenic impacts. On the one hand, continental margins in this region are bordered by the world's most densely populated coastal communities and receive tremendous amount of land-derived materials. On the other hand, the Kuroshio, the strong western boundary current of the North Pacific Ocean, which is modulated by climate oscillation, exerts strong influences over all three marginal seas. Because these continental margins sustain arguably some of the most productive marine ecosystems in the world, changes in these stressed ecosystems may threaten the livelihood of a large population of humans. This special issue reports the latest observations of the biogeochemical conditions and ecosystem functions in the three marginal seas. The studies exemplify the many faceted ecosystem functions and biogeochemical expressions, but they reveal only a few long-term trends mainly due to lack of sufficiently long records of well-designed observations. It is critical to develop and sustain time series observations in order to detect biogeochemical changes and ecosystem responses in continental margins and to attribute the causes for better management of the environment and resources in these marginal seas.

  11. Defensive externality and blame projection following failure.

    Science.gov (United States)

    Hochreich, D J

    1975-09-01

    This study focuses upon the relationship between internal-external control and defensive blame projection. Trust was used as a moderator variable for making differential predictions concerning the behavior of two subgroups of externals: defensive externals, whose externality is presumed to reflect primarily a verbal technique of defense, and congruent externals, whose externality reflects a more genuine belief that most outcomes are determined by forces beyond their personal control. As predicted, defensive externals showed a stronger tendency than did congruent externals and internals to resort to blame projection following failure at an achievement task. There were no group differences in attribution following task success. Defensive externals were found to be more responsive to negative feedback than were congruent externals.

  12. Ultraviolet microbeam irradiations of epithelial and spermatocyte spindles suggest that forces act on the kinetochore fibre and are not generated by its disassembly.

    Science.gov (United States)

    Spurck, T; Forer, A; Pickett-Heaps, J

    1997-01-01

    Ultraviolet (UV) microbeam irradiations of crane-fly spermatocyte and newt epithelial spindles severed kinetochore fibres (KT-fibres), creating areas of reduced birefringence (ARBs): the remnant KT-fibre consists of two "stubs," a pole-stub attached to the pole and a KT-stub attached to the kinetochore. KT-stubs remained visible but pole-stubs soon became undetectable [Forer et al., 1996]. At metaphase, in both cell types the KT-stub often changed orientation immediately after irradiation and its tip steadily moved poleward. In spermatocytes, the chromosome attached to the KT-stub remained at the equator as the KT-stub elongated. In epithelial cells, the KT-stub sometimes elongated as the associated chromosome remained at the equator; other times the associated chromosome moved poleward together with the KT-stub, albeit only a short distance toward the pole. When an ARB was generated at anaphase, chromosome(s) with a KT-stub often continued to move poleward. In spermatocytes, this movement was accompanied by steady elongation of the KT-stub. In epithelial cells, chromosomes accelerated polewards after irradiation until the KT-stubs reached the pole, after which chromosome movement returned to normal speeds. In some epithelial cells fine birefringent fibres by chance were present along one edge of ARBs; these remnant fibres buckled and broke as the KT-stub and chromosome moved polewards. Similarly, KT-stubs that moved into pole stubs (or astral fibres) caused the pole stubs (or astral fibres) to bend sharply from the point of impact. Our results contradict models of chromosome movement that postulate that force is generated by the kinetochore disassembling the KT-fibre. Instead, these results suggest that poleward directed forces act on the KT-fibre and the KT-stub and suggest that continuity of microtubules between kinetochore and pole is not obligatory for achieving anaphase motion to the pole.

  13. Empirical Evaluation On External Debt Of Malaysia

    OpenAIRE

    Nor’Aznin Abu Bakar; Sallahuddin Hassan

    2011-01-01

    This study analyzes the effects of external debts on economic growth in Malaysia. The analysis is conducted both at aggregate and disaggregate levels. The empirical results are based on VAR estimates using GDP, external debts, capital accumulation, labor force and human capital. Estimation results at the aggregate level indicate that total external debts affect economic growth positively. In particular, one percentage point increase in total external debts generates 1.29 percentage point of e...

  14. [Bilateral eye injuries by external transversal force].

    Science.gov (United States)

    Geidel, K; Schob, S; Unterlauft, J D; Wiedemann, P; Meier, P

    2016-12-14

    A 49-year-old female victim of violent crime with an acute bilateral loss of vision was referred to our hospital. The ophthalmological evaluation showed complete subconjunctival hemorrhage of both eyes, bilateral hemophthalmos and hypotonia of the left eye. These raised the suspicion of an occult scleral rupture. We immediately performed exploratory surgery and found a perforating scleral lesion of the left eye and a penetrating scleral lesion of the right eye. Furthermore, a small, cruciform wound was detected on the left temple. In cooperation with the department of radiology, the extraordinary injury pattern was reconstructed: a horizontal stab wound with perforation of the left eye and penetration of the right eye caused by a screwdriver. Visual rehabilitation necessitated further surgical interventions. Besides the intraoperative approach, immediate primary wound management within 100 h of trauma plays a pivotal role for long-term outcome.

  15. Forces predicted at the ankle during running.

    Science.gov (United States)

    Burdett, R G

    1982-01-01

    A biomechanical model of the ankle joint was developed and was used to predict the forces at the ankle during the stance phase of running. Measurements from five cadavers were averaged to obtain insertion points and directions of pull of equivalent tendons with respect to the assumed center of the ankle joint. A minimum joint force solution was obtained by assuming that only two equivalent muscle groups could exert force at one time. Three subjects ran at 4.47 m/s across a force platform that recorded the external forces and moments acting on the foot. Cinematography was used to measure the foot and leg positions during stance. Peak resultant joint forces ranging from 9.0 to 13.3 times body weight and peak Achilles tendon forces ranging from 5.3 to 10.0 times body weight were predicted. Small variations in some cases resulted in large differences in predicted forces. The highest tendon forces predicted exceeded those reported to cause damage to cadaver tendons in other studies.

  16. External Otitis (Swimmer's Ear)

    Science.gov (United States)

    ... to Pneumococcal Vaccine Additional Content Medical News External Otitis (Swimmer's Ear) By Bradley W. Kesser, MD, Associate ... the Outer Ear Ear Blockages Ear Tumors External Otitis (Swimmer's Ear) Malignant External Otitis Perichondritis External otitis ...

  17. Experimental Research on the Uplift Force Acted on the Spillway Chute Slabs%溢洪道陡槽底板上举力特性试验研究

    Institute of Scientific and Technical Information of China (English)

    李树宁; 杨敏; 李会平; 董天松

    2016-01-01

    基于某水电站溢洪道陡槽底板的稳定性试验研究,研究了溢洪道陡槽底板的上举力特性。分析结果表明:陡槽底板块单位面积上举力大小随着流能比 R增大而增大;底板块上举力最大值随错台高度Δ的增大有大幅增长,上举力标准差随错台高度Δ的增大有小幅增长;底板块上举力标准差和上举力最大值随着相对错台高度的增大而呈减小趋势;陡槽底板上举力概率密度基本符合正态分布;上举力优势频率集中在低频,底板块不会发生共振破坏;陡槽板块面积越大,单位面积最大上举力越小,研究成果可为设计人员提供科学的理论依据,同时可用于评估结构的稳定性。%In order to study the stability of the spillway chute slabs ,the characteristics of uplift force acted on the spillway chute slabs are investigated by performing model tests .Based on the model test results ,uplift force in unit area acted on the spillway chute slabs increases as the flow-energy ratio (R) elevated .The irregularity has a significant effect on uplift force acted on the spillway chute slabs .The standard deviation and maximum of uplift force increase as the irregularity height elevates ,at the same time ,the standard deviation and maximum of uplift force decrease as the relative irregularity height increases .Probability density of uplift force is in ac‐cordance with normal distribution .The dominant frequency of uplift force distributed in low frequency .The smaller the maximum of uplift force is ,the bigger the area of chute slabs is .

  18. Force Density Balance inside the Hydrogen Atom

    CERN Document Server

    Himpsel, F J

    2015-01-01

    Motivated by the long-debated question about the internal stability of the electron, the force densities acting on the charge density of the 1s electron in the H atom are investigated. The problem is mapped onto the canonical formalism for a classical Dirac field coupled to the electric field of an external point charge. An explicit calculation shows that the attractive Coulomb force density is balanced exactly at every point in space by the repulsive confinement force density. The latter requires evaluating the divergence of the stress tensor for the 1s solution of the Dirac equation. Such a local force balance goes beyond the global stability criteria that are usually given for the H atom. This concept is extended to the internal stability of any charged particle by investigating the force densities acting on its surrounding vacuum polarization. At large distances one has to consider only the charge density of virtual electrons and positrons, induced by a point charge in the vacuum of quantum electrodynamic...

  19. Analysis of Lorentz Force Act on Different Shapes Motionless Armature of P-MFCG%静态下 P-MFCG的不同形状电枢受力的仿真

    Institute of Scientific and Technical Information of China (English)

    李鹤; 吕庆敖; 李治源; 陶青青

    2011-01-01

    活塞式磁通压缩发电机(P-MFCG)作为一种可重复使用的脉冲功率发电机,在电磁发射器的供电电源方面具有广阔的应用前景.发电机电枢上所受的洛伦兹力(电磁力)对发电机的发电效能有至关重要的影响.不同形状的电枢对螺旋线圈内部磁场强度和位形分布的影响不同,在螺旋线圈内所受的洛伦兹力也不同.该文首先对电枢的受力和作用进行了理论分析,得出影响发电效率的是电枢所受洛伦兹力的轴向分量.其次,通过理论计算,得出电枢表面所受轴向力最大时,电枢表面元法向矢量与该处磁感应线矢量应当满足的关系.然后,利用电磁场有限元分析软件Ansoft,对五种不同形状电枢上感应涡流所受的洛伦兹力进行了仿真.所得数据表明圆柱状电枢所受的轴向洛伦兹力最大,锥状次之,是其70%,但都是分布在电枢的棱边上;类半椭球状电枢受力最小,但分布最均匀;而另外两种电枢的形状相比之下没有优势,不可取.这些结论为电枢的优化设计提供了理论依据,也为P-MFCG的进一步研究提供了重要参考.%As a kind of pulse generator, piston-type magnetic flux compression generator ( P-MFCG is suitable for the electromagnetic launcher. The Lorentz force acting on armature influence the generate efficiency.The shape of armature is a critical parameter, which helps to decide the distribution and intensity of magnetic field in helix winding region. With different shapes, the armatures induct different eddy currents and act different magnetic force ( Lorentz force). In this paper, analyzed the force acting on armature when it's sliding, and concluded that the bigger the Lorentz force along axial direction acted on armature, the higher the generate efficiency was. And the Lorentz force along axial direction act on armature was discovered to reach a peak value, only when the normal vector of armature infinitesimal surface and the vector of

  20. Adaptive external torque estimation by means of tracking a Lyapunov function

    Energy Technology Data Exchange (ETDEWEB)

    Schaub, H.; Junkins, J.L. [Texas A and M Univ., College Station, TX (United States); Robinett, R.D. [Sandia National Labs., Albuquerque, NM (United States)

    1996-03-01

    A real-time method is presented to adoptively estimate three-dimensional unmodeled external torques acting on a spacecraft. This is accomplished by forcing the tracking error dynamics to follow the Lyapunov function underlying the feedback control law. For the case where the external torque is constant, the tracking error dynamics are shown to converge asypmtotically. The methodology applies not only to the control law used in this paper, but can also be applied to most Lyapunov derived feedback control laws. The adaptive external torque estimation is very robust in the presence of measurement noise, since a numerical integration is used instead of a numerical differentiation. Spacecraft modeling errors, such as in the inertia matrix, are also compensated for by this method. Several examples illustrate the practical significance of these ideas.

  1. The External Degree.

    Science.gov (United States)

    Houle, Cyril O.

    This book examines the external degree in relation to the extremes of attitudes, myths, and data. Emphasis is placed on the emergence of the American external degree, foreign external-degree programs, the purpose of the external degree, the current scene, institutional issues, and problems of general policy. (MJM)

  2. Multidisciplinary Health Services as External Agents of Change

    DEFF Research Database (Denmark)

    Westerholm, Peter; Hasle, Peter; Fortuin, Rick

    2000-01-01

    A discussion of the possibilities for professionals from the occupational health service to act as external agents of change in introducing preventive activities in enterprises.......A discussion of the possibilities for professionals from the occupational health service to act as external agents of change in introducing preventive activities in enterprises....

  3. STATUTORY INTERPRETATION - TRAFFICKING VICTIMS PROTECTION ACT OF 2000 - SIXTH CIRCUIT DECLINES TO EXTEND FEDERAL FORCED LABOR STATUTE TO CONDUCT CRIMINALIZED UNDER STATE LAW, BASED IN PART ON FEDERALISM CONCERNS. - United States v. Toviave, 761 F.3d 623 (6th Cir. 2014)

    National Research Council Canada - National Science Library

    2015-01-01

    .... Toviave, the Sixth Circuit relied on this notion of traditional state power in holding that a forced labor provision of the Trafficking Victims Protection Act of 2000 did not apply to a defendant who...

  4. Forced Migration and Global Responsibility for Health; Comment on “Defining and Acting on Global Health: The Case of Japan and the Refugee Crisis”

    Directory of Open Access Journals (Sweden)

    Kayvan Bozorgmehr

    2017-07-01

    Full Text Available Forced migration has become a world-wide phenomenon in the past century, affecting increasing numbers of countries and people. It entails important challenges from a global health perspective. Leppold et al have critically discussed the Japanese interpretation of global responsibility for health in the context of forced migration. This commentary complements their analysis by outlining three priority areas of global health responsibility for European Union (EU countries. We highlight important stages of the migration phases related to forced migration and propose three arguments. First, the chronic neglect of the large number of internally displaced persons (IDPs in the discourses on the “refugee crisis” needs to be corrected in order to develop sustainable solutions with a framework of the Sustainable Development Goals (SDGs. Second, protection gaps in the global system of protection need to be effectively closed to resolve conflicts with border management and normative global health frameworks. Third, effective policies need to be developed and implemented to meet the health and humanitarian needs of forced migrants; at the same time, the solidarity crisis within the EU needs to be overcome. These stakes are high. EU countries, being committed to global health, should urgently address these areas.

  5. Forced Migration and Global Responsibility for Health Comment on "Defining and Acting on Global Health: The Case of Japan and the Refugee Crisis".

    Science.gov (United States)

    Bozorgmehr, Kayvan; Razum, Oliver

    2016-11-05

    Forced migration has become a world-wide phenomenon in the past century, affecting increasing numbers of countries and people. It entails important challenges from a global health perspective. Leppold et al have critically discussed the Japanese interpretation of global responsibility for health in the context of forced migration. This commentary complements their analysis by outlining three priority areas of global health responsibility for European Union (EU) countries. We highlight important stages of the migration phases related to forced migration and propose three arguments. First, the chronic neglect of the large number of internally displaced persons (IDPs) in the discourses on the "refugee crisis" needs to be corrected in order to develop sustainable solutions with a framework of the Sustainable Development Goals (SDGs). Second, protection gaps in the global system of protection need to be effectively closed to resolve conflicts with border management and normative global health frameworks. Third, effective policies need to be developed and implemented to meet the health and humanitarian needs of forced migrants; at the same time, the solidarity crisis within the EU needs to be overcome. These stakes are high. EU countries, being committed to global health, should urgently address these areas. © 2017 The Author(s); Published by Kerman University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

  6. Forces in molecules.

    Science.gov (United States)

    Hernández-Trujillo, Jesús; Cortés-Guzmán, Fernando; Fang, De-Chai; Bader, Richard F W

    2007-01-01

    Chemistry is determined by the electrostatic forces acting within a collection of nuclei and electrons. The attraction of the nuclei for the electrons is the only attractive force in a molecule and is the force responsible for the bonding between atoms. This is the attractive force acting on the electrons in the Ehrenfest force and on the nuclei in the Feynman force, one that is countered by the repulsion between the electrons in the former and by the repulsion between the nuclei in the latter. The virial theorem relates these forces to the energy changes resulting from interactions between atoms. All bonding, as signified by the presence of a bond path, has a common origin in terms of the mechanics determined by the Ehrenfest, Feynman and virial theorems. This paper is concerned in particular with the mechanics of interaction encountered in what are classically described as 'nonbonded interactions'--are atoms that 'touch' bonded or repelling one another?

  7. A Table-Shaped Tactile Sensor for Detecting Triaxial Force on the Basis of Strain Distribution

    Science.gov (United States)

    Lee, Jeong Il; Kim, Min-Gyu; Shikida, Mitsuhiro; Sato, Kazuo

    2013-01-01

    A slim and flexible tactile sensor applicable to the interaction of human and intelligent robots is presented. In particular, a simple sensing principle for decoupling of three-dimensional force is proposed. Sensitivity of the proposed tactile sensor is tested experimentally. To improve the sensitivity of the sensor, a table-shaped sensing element was designed. Table-shaped structure can convert an external acting force into concentrated internal stress. A “triaxial force decoupling algorithm” was developed by combining two-dimensional mapping data calculated by finite element analysis. The sensor was calibrated under normal and tangential forces. The external loads applied to the sensor could be decoupled independently as a function of the strain-gauge responses. PMID:24287546

  8. Development of a Mechanism for Measuring Forces and Aligning Moment Acting on the Steering Wheels of a Four-Wheel Vehicle

    Directory of Open Access Journals (Sweden)

    A Hajiahmad

    2014-09-01

    Full Text Available In this paper, a low-cost dynamometer for rolling, steered wheels is described. The dynamometer was constructed to determine whether such an instrumented mechanism was practical. Four S-beam load cells, an Opto-counter and a potentiometer were used to obtain all moments, and forces using dynamic and kinematic analysis. Minimal simplifying assumptions considered for the required calculations. Overturning, aligning and rolling resistance moments besides vertical force are directly measured by the load cells. The Opto-counter detects wheel angular velocity and the potentiometer was used to measure the steering angle. The results showed that the mechanism was very well calibrated with a coefficient of determination of over 0.99 and can be used to define wheel dynamic behavior.

  9. Regulating multiple externalities

    DEFF Research Database (Denmark)

    Waldo, Staffan; Jensen, Frank; Nielsen, Max

    2016-01-01

    Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory instrume......Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory...

  10. ExternE National Implementation Finland

    Energy Technology Data Exchange (ETDEWEB)

    Pingoud, K.; Maelkki, H.; Wihersaari, M.; Pirilae, P. [VTT Energy, Espoo (Finland); Hongisto, M. [Imatran Voima Oy, Vantaa (Finland); Siitonen, S. [Ekono Energy Ltd, Espoo (Finland); Johansson, M. [Finnish Environment Institute, Helsinki (Finland)

    1999-07-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  11. ASH External Web Portal (External Portal) -

    Data.gov (United States)

    Department of Transportation — The ASH External Web Portal is a web-based portal that provides single sign-on functionality, making the web portal a single location from which to be authenticated...

  12. [The effect of the motion of forefoot joint at the force exerted upon the floor during walking exercise].

    Science.gov (United States)

    Maeda, A; Nishizono, H; Ebashi, H; Shibayama, H

    1993-11-01

    In walking exercise the human body is exposed to external forces. Some of them are produced by constraints such as surface, shoes or opponent. In kick action of walking, the ground reaction force (GRF) is the most important external force. The magnitude of the GRF, its direction, and point of application have an influence on the load on the human body. The purpose of this study is to clarify the role of forefoot joint (artt. metatarsophalangeae) at the force exerted upon the floor during kick action of walking. The device used in this study to analyze the GRF and its three components consists of Kistler's force platform. Output from force transducer was collected online with a TEAC data recorder and MEM-4101 minicomputer. The impact force measurements were taken from the anterior-posterior force time curves at the take-off for 1 subject walking 10 trials at 2 m/sec with 2 different pairs of shoes (Shoes 1: thin sole of 4mm, and Shoes 2: thick sole of 40mm) and without shoes. High speed (200f/sec) cinematography was also used to analyze the angular displacement of forefoot joint at the take-off of walking exercise. The force acting at the forefoot joint may produce the anterior-posterior force of the GRF which is defined as the propelling power acting on the human body during walking exercise. The result showed that the impact force peak occurred 40-60 msec before take-off and the propelling part of kick action accounted for only about 6% of the external force.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. The wall shear force on a liquid droplet adhering to a solid surface under an imposed shear

    Science.gov (United States)

    Shabtay, Royi; Frankel, Itzchak

    2011-11-01

    We focus on large droplet viscosities typical of those appearing in the upper respiratory tract of CF or chronically ventilated patients. To further simplify the problem we assume vanishingly small capillary numbers and consider (non-deformable) hemispherical droplets. Under these assumptions the problem decouples into (i) the external problem of imposed shear flow over a planar solid wall with a hemispherical protuberance which is simulated by means of a commercially available finite - volume code and (ii) the inner Stokes flow animated by the now prescribed shear stress distribution over the liquid surface. The latter problem is addressed through use of series expansions in spherical harmonics. The interaction between the caterpillar inner - fluid motion and the solid substrate results in a shear force adding to the external - flow drag force acting in the downstream direction. Throughout the range of outer - flow Reynolds numbers considered (0.05-50) this interaction contributes over 35% of the total hydrodynamic force acting to dislodge the droplet.

  14. Analysis of acting forces resulting from armhole structure of man's suit%西服袖窿结构的作用力分析

    Institute of Scientific and Technical Information of China (English)

    陈谦; 程军红; 庹武

    2011-01-01

    The relationship between the structural condition and the ready-made form of armhole is nonlinear. Through analyzing the armhole structure of man's suit, a mechanical model of the lower armhole is established, and a relationship between different forces and parameters of armhole is built. To analyze the different structural allocation of man's suit armhole and the deformation pattern of the different structural allocation, a large number of samples are tested, and the effect of the force of tangent line, normal and tensional stress on the local stability and smooth comfort of man's suit armhole are obtained.The relationships between different forces and parameter of armhole are analyzed by utilizing the mechanical model. A theoretical optimization scheme has been proposed for achieving the unity of mould and comfort of sleeves.%袖窿部位的结构条件和成品形态之间是复杂的非线性关系,通过对男西服袖窿结构进行分析,建立了一种下部袖窿的力学模型,构建了不同作用力与袖窿参数间的相互关系.为分析男西服袖窿部位的不同结构配置以及在不同配置下的袖窿变形规律,通过大量样本测试,获得男西服袖窿切线力、法线力和扭力对袖窿局部稳定性和平顺性的影响,应用力学模型分析了不同作用力与袖窿参数间的相互关系,从而对袖窿结构配置提出理论优化方案,以达到肩袖部位造型性和着装舒适性的统一.

  15. Tangential finger forces use mechanical advantage during static grasping.

    Science.gov (United States)

    Slota, Gregory P; Latash, Mark L; Zatsiorsky, Vladimir M

    2012-02-01

    When grasping and manipulating objects, the central controller utilizes the mechanical advantage of the normal forces of the fingers for torque production. Whether the same is valid for tangential forces is unknown. The main purpose of this study was to determine the patterns of finger tangential forces and the use of mechanical advantage as a control mechanism when dealing with objects of nonuniform finger positioning. A complementary goal was to explore the interaction of mechanical advantage (moment arm) and the role a finger has as a torque agonist/antagonist with respect to external torques (±0.4 N m). Five 6-df force/torque transducers measured finger forces while subjects held a prism handle (6 cm width × 9 cm height) with and without a single finger displaced 2 cm (handle width). The effect of increasing the tangential moment arm was significant (p forces (in >70% of trials) and hence creating greater moments. Thus, the data provides evidence that the grasping system as a rule utilizes mechanical advantage for generating tangential forces. The increase in tangential force was independent of whether the finger was acting as a torque agonist or antagonist, revealing their effects to be additive.

  16. A five-year assessment of the affordable care act: market forces still trump the common good in U.S. Health care.

    Science.gov (United States)

    Geyman, John P

    2015-01-01

    The Affordable Care Act (ACA) was enacted in 2010 as the signature domestic achievement of the Obama presidency. It was intended to contain costs and achieve near-universal access to affordable health care of improved quality. Now, five years later, it is time to assess its track record. This article compares the goals and claims of the ACA with its actual experience in the areas of access, costs, affordability, and quality of care. Based on the evidence, one has to conclude that containment of health care costs is nowhere in sight, that more than 37 million Americans will still be uninsured when the ACA is fully implemented in 2019, that many more millions will be underinsured, and that profiteering will still dominate the culture of U.S. health care. More fundamental reform will be needed. The country still needs to confront the challenge that our for-profit health insurance industry, together with enormous bureaucratic waste and widespread investor ownership throughout our market-based system, are themselves barriers to health care reform. Here we consider the lessons we can take away from the ACA's first five years and lay out the economic, social/political, and moral arguments for replacing it with single-payer national health insurance.

  17. 受恒力作用的相对论粒子的动力学方程的解%A Simple Solution to the Dynamic Equation for a Relativistic Particle Acted by a Constant Force

    Institute of Scientific and Technical Information of China (English)

    黄时中; 方燕

    2011-01-01

    用一种简洁的数学形式给出了受恒力作用的粒子的相对论动力学方程的解,解决了相对论中的抛体运动问题,详细讨论了相对论粒子的加速度、速度和运动方程与牛顿力学中对应物理量的区别和联系.%A concise solution to the dynamic equation for a relativistic particle acted by a constant force is presented,which is corresponding to the projectile motion in special relativity,the acceleration,velocity and equation of motion are expressed by easy functions,the differences and relations between special relativity and Newton's Mechanics are analyzed in detail.

  18. Rat Liver Enzyme Release Depends on Blood Flow-Bearing Physical Forces Acting in Endothelium Glycocalyx rather than on Liver Damage

    Directory of Open Access Journals (Sweden)

    Julieta A. Díaz-Juárez

    2017-01-01

    Full Text Available We have found selective elevation of serum enzyme activities in rats subjected to partial hepatectomy (PH, apparently controlled by hemodynamic flow-bearing physical forces. Here, we assess the involvement of stretch-sensitive calcium channels and calcium mobilization in isolated livers, after chemical modifications of the endothelial glycocalyx and changing perfusion directionality. Inhibiting in vivo protein synthesis, we found that liver enzyme release is influenced by de novo synthesis of endothelial glycocalyx components, and released enzymes are confined into a liver “pool.” Moreover, liver enzyme release depended on extracellular calcium entry possibly mediated by stretch-sensitive calcium channels, and this endothelial-mediated mechanotransduction in liver enzyme release was also evidenced by modifying the glycocalyx carbohydrate components, directionality of perfusing flow rate, and the participation of nitric oxide (NO and malondialdehyde (MDA, leading to modifications in the intracellular distribution of these enzymes mainly as nuclear enrichment of “mitochondrial” enzymes. In conclusion, the flow-induced shear stress may provide fine-tuned control of released hepatic enzymes through mediation by the endothelium glycocalyx, which provides evidence of a biological role of the enzyme release rather to be merely a biomarker for evaluating hepatotoxicity and liver damage, actually positively influencing progression of liver regeneration in mammals.

  19. Rat Liver Enzyme Release Depends on Blood Flow-Bearing Physical Forces Acting in Endothelium Glycocalyx rather than on Liver Damage

    Science.gov (United States)

    Díaz-Juárez, Julieta A.

    2017-01-01

    We have found selective elevation of serum enzyme activities in rats subjected to partial hepatectomy (PH), apparently controlled by hemodynamic flow-bearing physical forces. Here, we assess the involvement of stretch-sensitive calcium channels and calcium mobilization in isolated livers, after chemical modifications of the endothelial glycocalyx and changing perfusion directionality. Inhibiting in vivo protein synthesis, we found that liver enzyme release is influenced by de novo synthesis of endothelial glycocalyx components, and released enzymes are confined into a liver “pool.” Moreover, liver enzyme release depended on extracellular calcium entry possibly mediated by stretch-sensitive calcium channels, and this endothelial-mediated mechanotransduction in liver enzyme release was also evidenced by modifying the glycocalyx carbohydrate components, directionality of perfusing flow rate, and the participation of nitric oxide (NO) and malondialdehyde (MDA), leading to modifications in the intracellular distribution of these enzymes mainly as nuclear enrichment of “mitochondrial” enzymes. In conclusion, the flow-induced shear stress may provide fine-tuned control of released hepatic enzymes through mediation by the endothelium glycocalyx, which provides evidence of a biological role of the enzyme release rather to be merely a biomarker for evaluating hepatotoxicity and liver damage, actually positively influencing progression of liver regeneration in mammals. PMID:28337244

  20. External radiation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report describes how external radiation was measured, how surveys were performed, and the results of these measurements and surveys. External radiation exposure rates were measured at locations on and off the Hanford Site using thermoluminescent dosimeters (TLD). External radiation and contamination surveys were also performed with portable radiation survey instruments at locations on and around the Hanford Site.

  1. Modelling Inter-Particle Forces and Resulting Agglomerate Sizes in Cement-Based Materials

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Geiker, Mette Rica

    2005-01-01

    The theory of inter-particle forces versus external shear in cement-based materials is reviewed. On this basis, calculations on maximum agglomerate size present after the combined action of superplasticizers and shear are carried out. Qualitative experimental results indicate that external shear...... affects the particle size distribution of Mg(OH)2 (used as model material) as well as silica, whereas the addition of superplasticizers affects only the smallest particles in cement and thus primarily acts as water reducers and not dispersers....

  2. Nonlinear Dynamic Force Spectroscopy

    CERN Document Server

    Björnham, Oscar

    2016-01-01

    Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information of the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear regime. For example, bacterial adhesion pili and polymers with worm-like chain properties are examples of structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory we modeled a bio-complex expressed on a stiff, an elastic and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found th...

  3. Privacy Act

    Science.gov (United States)

    Learn about the Privacy Act of 1974, the Electronic Government Act of 2002, the Federal Information Security Management Act, and other information about the Environmental Protection Agency maintains its records.

  4. Influence of external potentials on heterogeneous diffusion processes

    Science.gov (United States)

    Kazakevičius, Rytis; Ruseckas, Julius

    2016-09-01

    In this paper we consider heterogeneous diffusion processes with the power-law dependence of the diffusion coefficient on the position and investigate the influence of external forces on the resulting anomalous diffusion. The heterogeneous diffusion processes can yield subdiffusion as well as superdiffusion, depending on the behavior of the diffusion coefficient. We assume that not only the diffusion coefficient but also the external force has a power-law dependence on the position. We obtain analytic expressions for the transition probability in two cases: when the power-law exponent in the external force is equal to 2 η -1 , where 2 η is the power-law exponent in the dependence of the diffusion coefficient on the position, and when the external force has a linear dependence on the position. We found that the power-law exponent in the dependence of the mean square displacement on time does not depend on the external force; this force changes only the anomalous diffusion coefficient. In addition, the external force having the power-law exponent different from 2 η -1 limits the time interval where the anomalous diffusion occurs. We expect that the results obtained in this paper may be relevant for a more complete understanding of anomalous diffusion processes.

  5. Force among magnetic nanocylinders trapped in triangular arrays

    Energy Technology Data Exchange (ETDEWEB)

    Cisternas, E., E-mail: ecisternas@ufro.cl [Departamento de Ciencias Fisicas, Universidad de La Frontera, Casilla 54-D, Temuco (Chile); Vasquez, Y.; Vogel, E.E. [Departamento de Ciencias Fisicas, Universidad de La Frontera, Casilla 54-D, Temuco (Chile)

    2012-03-15

    We study the effect of the forces among magnetic nanocylinders trapped in a membrane such as those used to produce them. The interaction force between two parallel and identical magnetic nanocylinders is revisited to obtain expressions that can later be used to add them both in a discrete and a continuum approximation. At this point a particular geometry has to be assumed and we use a particular configuration reported in the literature, namely, a bundle of parallel magnetic cylinders trapped in a circular membrane. When a strong enough external magnetic field is imposed along the axis of the membrane (also along the axes of the cylinders) all magnetizations point along this direction and cylinders repel among themselves. In a first approximation we will consider a soft enough membrane so energy is mostly relaxed through a deformation of the membrane leaving the magnetization of the cylinders basically as it was in the absence of external field. Then we obtain the forces among these cylinders by two methods: one summing the contributions of a discrete number of objects and another one in which we consider a continuum distribution of them to reach larger systems. Numerical evaluation of these forces can reach 50 mdyn approximately. Such forces will act on the membrane at the positions of the magnetic cylinders; in the case of a circular silicon membrane of radius 1.0 mm the radial expansion of the membrane can be of the order of 1 nm. This effect could be larger for softer membranes. A discussion of experimental techniques to detect this phenomenon is also done followed by the proposal of a possible application. - Highlights: Black-Right-Pointing-Pointer Force among magnetic nanocylinders ordered in triangular arrays within a membrane. Black-Right-Pointing-Pointer Macroscopic effect on a membrane containing cylinders by applying an external magnetic field. Black-Right-Pointing-Pointer Membrane deformation due to magnetostatic interaction among cylinders.

  6. 76 FR 57897 - Energy Conservation Program: Energy Conservation Standards for Certain External Power Supplies

    Science.gov (United States)

    2011-09-19

    ... RIN 1904-AB57 Energy Conservation Program: Energy Conservation Standards for Certain External Power... exclude external power supplies used in specific applications from certain energy conservation standards prescribed under the Energy Policy and Conservation Act (EPCA). Congress enacted this exclusion,...

  7. Unsteady-State Grinding Technology (II) Experimental Studies of Grinding Forces and Force Ratio

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    As is known to all, grinding force is one of the most important parameters to evaluate the whole process of grinding. Generally, the grinding force is resolved to three component forces, namely, normal grinding force F n, tangential grinding force F t and a component force acting along the direction of longitudinal feed which is usually neglected because of insignificance. The normal grinding force F n has influence upon surface deformation and roughness of workpiece, while the tangential grinding force ...

  8. EXTERNAL MAGNETIC PULSE STRAIGHTENING – NEW TECHNOLOGY CAR BODY REPAIR

    Directory of Open Access Journals (Sweden)

    А. Gnatov

    2015-07-01

    Full Text Available Innovative equipment of external contactless magnetic impulse straightening developed by the laboratory of Electromagnetic Technology of Kharkiv National Automobile and Highway University is presented in this paper. The effect of metal hyper-plasticity at magnetic impulse acting is described. Suggestions concerning practical testing of advanced technology of damaged car body panels by external contactless magnetic impulse straightening are presented. The processing route of external contactless magnetic impulse straightening process is specified.

  9. Semantic Externalism and Self Knowledge: Privileged Access to the World

    OpenAIRE

    Sawyer, Sarah

    2008-01-01

    The thesis is concerned to defend the compatibility of two plausible claims about the mind; semantic externalism and privileged access. It is further concerned to demonstrate one important implication of the conjunction of semantic externalism and privileged access, an implication which forces the rejection of the dichotomy between knowledge of one’s mind and knowledge of one’s world. Chapter one is a presentation of semantic externalism. Chapter two is a presentation of the claim of privileg...

  10. Expert opinion: Comparative analysis of the social costs of electricity generation in the context of the Renewable Energy Sources Act (EEG); Gutachten: Vergleich externer Kosten der Stromerzeugung in Bezug auf das Erneuerbare Energien Gesetz

    Energy Technology Data Exchange (ETDEWEB)

    Hohmeyer, O.

    2002-03-01

    The expert opinion for the German Federal Environmental Agency explains and discusses the results of six scenarios describing the outcome of substitution of conventional electricity generation technologies relying exclusively on fossil fuels, using as a reference case the generation of middle load power in Germany in 1998 with the then operating German power plants, as well as projections for the year 2001. One major objective of the expert opinion is to evaluate results in terms of social and other relevant costs, achieved through the use of renewable energy technologies for electricity generation since effectiveness of the German EEG, (act promoting power generation from renewable energy sources). The comparative evaluation distinctly refers to conventional and renewable generation technologies in assessing their economic and environmental impacts. The second aspect analysed is the support (and its efficiency) offered so far by the existing national policies and laws, as well as the European Directives and guidelines on promotion of renewable energy technologies. Proposals for improvement are presented. (orig./CB) [German] Im Gutachten werden sechs Szenarien fuer die substituierte konventionelle Stromerzeugung entwickelt, die als Basis sowohl die durchschnittliche Stromerzeugung unter Verwendung fossiler Brennstoffe als auch die Erzeugung von Mittellaststrom fuer die Jahre 1998 und 2010 betrachten und anhand entsprechender Referenzsysteme und Berechnungen die Ergebnisse liefern, die die Frage nach allen relevanten, seit Einfuehrung des EEG bis heute, durch den Einsatz erneuerbarer Energietraeger substituierten Kosten und umweltrelevanten Verbesserungen beantworten und detailliert schildern. In der Zusammenfassung werden vor allem die Ergebnisse von Vergleichen bezogen auf verschiedene erneuerbare und konventioneller Energietraeger fuer das Mittellastszenario auf der Basis des fuer 1998 dokumentierten deutschen Kraftwerksparks vorgestellt. Ferner werden die

  11. Externally Verifiable Oblivious RAM

    Directory of Open Access Journals (Sweden)

    Gancher Joshua

    2017-04-01

    Full Text Available We present the idea of externally verifiable oblivious RAM (ORAM. Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM [15] and Ring ORAM [9] protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier.

  12. External Beam Therapy (EBT)

    Science.gov (United States)

    ... Esophageal Cancer Treatment Head and Neck Cancer Treatment Lung Cancer Treatment Prostate Cancer Treatment Brain Tumor Treatment Why is ... Radiation Oncology) Breast Cancer Treatment Esophageal Cancer Treatment Lung Cancer Treatment Images related to External Beam Therapy (EBT) Sponsored ...

  13. MALIGNANT EXTERNAL OTITIS

    OpenAIRE

    Massoud Moghaddam

    1993-01-01

    Two case reports of malignant external otitis in the elderly diabetics and their complications and management with regard to our experience at Amir Alam Hospital, Department of ENT will be discussed here.

  14. Checklists for external validity

    DEFF Research Database (Denmark)

    Dyrvig, Anne-Kirstine; Kidholm, Kristian; Gerke, Oke;

    2014-01-01

    RATIONALE, AIMS AND OBJECTIVES: The quality of the current literature on external validity varies considerably. An improved checklist with validated items on external validity would aid decision-makers in judging similarities among circumstances when transferring evidence from a study setting...... to an implementation setting. In this paper, currently available checklists on external validity are identified, assessed and used as a basis for proposing a new improved instrument. METHOD: A systematic literature review was carried out in Pubmed, Embase and Cinahl on English-language papers without time restrictions....... The retrieved checklist items were assessed for (i) the methodology used in primary literature, justifying inclusion of each item; and (ii) the number of times each item appeared in checklists. RESULTS: Fifteen papers were identified, presenting a total of 21 checklists for external validity, yielding a total...

  15. Migration with fiscal externalities.

    Science.gov (United States)

    Hercowitz, Z; Pines, D

    1991-11-01

    "This paper analyses the distribution of a country's population among regions when migration involves fiscal externalities. The main question addressed is whether a decentralized decision making [by] regional governments can produce an optimal population distribution...or a centralized intervention is indispensable, as argued before in the literature.... It turns out that, while with costless mobility the fiscal externality is fully internalized by voluntary interregional transfers, with costly mobility, centrally coordinated transfers still remain indispensable for achieving the socially optimal allocation."

  16. Sen cycles and externalities

    OpenAIRE

    Piggins, Ashley; Salerno, Gillian

    2016-01-01

    It has long been understood that externalities of some kind are responsible for Sen’s (1970) theorem on the impossibility of a Paretian liberal. However, Saari and Petron (2006) show that for any social preference cycle generated by combining the weak Pareto principle and individual decisiveness, every decisive individual must suffer at least one strong negative externality. We show that this fundamental result only holds when individual preferences are strict. Building on their contribution,...

  17. Simulations of polymer brushes with charged end monomers under external electric fields

    Science.gov (United States)

    Ding, Huanda; Duan, Chao; Tong, Chaohui

    2017-01-01

    Using Langevin dynamics simulations, the response of neutral polymer brushes with charged terminal monomers to external electric fields has been investigated. The external electric field is equivalent to the field generated by the opposite surface charges on two parallel electrodes. The effects of charge valence of terminal monomers on the structure of double layers and overall charge balance near the two electrodes were examined. Using the charge density distributions obtained from simulations, the total electric field normal to the electrodes was calculated by numerically solving the Poisson equation. Under external electric fields, the total electric field across the two electrodes is highly non-uniform and in certain regions within the brush, the total electric field nearly vanishes. The probability distribution of electric force acting on one charged terminal monomer was obtained from simulations and how it affects the probability density distribution of terminal monomers was analyzed. The response of polymer brushes with charged terminal monomers to a strongly stretching external electric field was compared with that of uniformly charged polymer brushes.

  18. Dynamic inversion enables external magnets to concentrate ferromagnetic rods to a central target.

    Science.gov (United States)

    Nacev, A; Weinberg, I N; Stepanov, P Y; Kupfer, S; Mair, L O; Urdaneta, M G; Shimoji, M; Fricke, S T; Shapiro, B

    2015-01-14

    The ability to use magnets external to the body to focus therapy to deep tissue targets has remained an elusive goal in magnetic drug targeting. Researchers have hitherto been able to manipulate magnetic nanotherapeutics in vivo with nearby magnets but have remained unable to focus these therapies to targets deep within the body using magnets external to the body. One of the factors that has made focusing of therapy to central targets between magnets challenging is Samuel Earnshaw's theorem as applied to Maxwell's equations. These mathematical formulations imply that external static magnets cannot create a stable potential energy well between them. We posited that fast magnetic pulses could act on ferromagnetic rods before they could realign with the magnetic field. Mathematically, this is equivalent to reversing the sign of the potential energy term in Earnshaw's theorem, thus enabling a quasi-static stable trap between magnets. With in vitro experiments, we demonstrated that quick, shaped magnetic pulses can be successfully used to create inward pointing magnetic forces that, on average, enable external magnets to concentrate ferromagnetic rods to a central location.

  19. ACTS 2014

    DEFF Research Database (Denmark)

    Co-curator of ACTS 2014 together with Rasmus Holmboe, Judith Schwarzbart and Sanne Kofoed. ACTS is the Museum of Contemporary Art’s international bi-annual festival. ACTS was established in 2011 and, while the primary focus is on sound and performance art, it also looks toward socially oriented art...... various possibilities and public spaces as a stage. ACTS takes place in and around the museum and diverse locations in Roskilde city. ACTS is partly curated by the museum staff and partly by guest curators. ACTS 2014 is supported by Nordea-fonden and is a part of the project The Museum goes downtown....

  20. Nanoscopic oxidation of p-type and un-doped Si (100) surfaces using un-externally biased atomic force microscope tips (AFM) in the presence of selected organic solvents

    Science.gov (United States)

    McCausland, Jeffrey; Withanage, Sajeevi; Mallik, Robert; Lyuksyutov, Sergei

    A conductive un-biased AFM tip oscillating above p-type or un-doped Si (100) treated with toluene, butan-2-ol, and propan-2-ol creates nanostructures ranging in height from 1-100 nm. The tip was oscillated in ambient conditions (30-70% Rel. Humidity) at frequencies in the 102 kHz range. It was repeatable with various concentrations of solvent in aqueous solution. It is suggested that mechanical oscillations of the AFM tip polarizes the solvent molecules deposited on the surface resulting in electron transfer from the tip to the surface followed by feature formation. This process effectively creates an electrochemical cell at the microscopic level and the miscibility of the solvents is the key to enabling the process. Species which ionize during the process may be consumed in irreversible reactions whereas the alcohols act as catalysts and are not consumed. The influence of boron defects in the Si substrates is also discussed. It appears that the observed oxidation is different from all other similar reported phenomena including local anodic oxidation, and chemo-mechanical lithographic techniques utilizing AFM.

  1. External Force Damage Simulation of Submarine High-voltage Cable Based on Distributed Fiber Optic Sensor Technology%基于分布式光纤传感技术的高压海底电缆外力损坏仿真

    Institute of Scientific and Technical Information of China (English)

    陆莹; 黄辉

    2012-01-01

    高压海底电缆的安全稳定运行对于海上能源的开发具有重要的作用,海缆电缆的损坏主要由外力引起,针对分布式光纤传感器在线监测高压海底电缆运行状况的方法,利用有限元软件ANSYS建立XLPE高压海底电缆模型,仿真分析海底电缆受到外力损坏时,内部物理量的变化,为分布式光纤传感器在线监测高压海底电缆运行状态提供参考。%Safety and stable operation of submarine high-voltage cable has played an important role in the development of Marine energy. However, submarine high-voltage cable was mainly damaged by external forces. According to the method for operation state of submarine high-voltage cable using on-line monitoring technology based on distributed fiber optic sensor, the model of the XLPE submarine high-voltage cable was gained by using finite element software ANSYS. Then, based on the model, the change of internal physical quantities were researched ,when submarine high-voltage cable was damaged by external force, with the function to provide the practical reference for running state of submarine high-voltage cable monitoring on-line based on distributed fiber optic sensor.

  2. Environmental external effects from wind power based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1998-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  3. Externality or sustainability economics?

    Energy Technology Data Exchange (ETDEWEB)

    Bergh, Jeroen C.J.M. van den [ICREA, Barcelona (Spain); Department of Economics and Economic History and Institute for Environmental Science and Technology, Universitat Autonoma de Barcelona (Spain)

    2010-09-15

    In an effort to develop 'sustainability economics' Baumgaertner and Quaas (2010) neglect the central concept of environmental economics-'environmental externality'. This note proposes a possible connection between the concepts of environmental externality and sustainability. In addition, attention is asked for other aspects of 'sustainability economics', namely the distinction weak/strong sustainability, spatial sustainability and sustainable trade, distinctive sustainability policy, and the ideas of early 'sustainability economists'. I argue that both sustainability and externalities reflect a systems perspective and propose that effective sustainability solutions require that more attention is given to system feedbacks, notably other-regarding preferences and social interactions, and energy and environmental rebound. The case of climate change and policy is used to illustrate particular statements. As a conclusion, a list of 20 insights and suggestions for research is offered. (author)

  4. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  5. Stochastic Control - External Models

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2005-01-01

    This note is devoted to control of stochastic systems described in discrete time. We are concerned with external descriptions or transfer function model, where we have a dynamic model for the input output relation only (i.e.. no direct internal information). The methods are based on LTI systems...

  6. Productivity Change and Externalities

    DEFF Research Database (Denmark)

    Kravtsova, Victoria

    2014-01-01

    firms and the economy as a whole. The approach used in the current research accounts for different internal as well as external factors that individual firms face and evaluates the effect on changes in productivity, technology as well as the efficiency of domestic firms. The empirical analysis focuses...... change in different types of firms and sectors of the economy...

  7. Multiple external root resorption.

    Science.gov (United States)

    Yusof, W Z; Ghazali, M N

    1989-04-01

    Presented is an unusual case of multiple external root resorption. Although the cause of this resorption was not determined, several possibilities are presented. Trauma from occlusion, periodontal and pulpal inflammation, and resorption of idiopathic origin are all discussed as possible causes.

  8. An Improved Force-Angle Stability Margin for Radial Symmetrical Hexapod Robot Subject to Dynamic Effects

    Directory of Open Access Journals (Sweden)

    Shidong Long

    2015-05-01

    Full Text Available This paper presents a study on stability monitoring for a radial symmetrical hexapod robot under dynamic conditions. The force-angle stability margin (FASM measure method has been chosen as the stability criterion. This is because it is suitable for the stability analysis, in terms of external forces or manipulator loads acting on the body. Considering that a radial symmetrical hexapod robot can tumble along the contact point besides tip-over axis, this paper proposes an improved FASM measure method. Furthermore, it provides the method for calculating the stability angle of contact point and simplifies the algorithm of FASM. To verify the improved FASM measure method, three potential dynamic situations have been simulated. The simulation results confirm that, under dynamic conditions, the improved FASM is efficient, simple in terms of calculation cost and sensitive to manipulator loads and external disturbances. This means it has practical value in on-line controllers.

  9. Predictability of Forced Lorenz Systems

    Science.gov (United States)

    Li, Baosheng; Ding, Ruiqiang; Li, Jianping; Zhong, Quanjia

    2017-04-01

    Based on the nonlinear local Lyapunov exponent (NLLE) approach, the influences of external forcing on the predictability are studied in the Lorenz systems with constant and quasi-periodic forces in this paper. The results indicate that for the Lorenz systems with constant and quasi-periodic forces, their predictability limits increase with the forcing strength. With the same magnitude and different directions, the constant or quasi-periodic forcing shows different effects on the predictability limit in the Lorenz system, and these effects become significant with the increase of the forcing strength. Generally speaking, the positive forcing leads to a higher predictability limit than the negative forcing. Therefore, when we think about the effects of positive and negative elements and phases in the atmosphere and ocean research, the predictability problems driven by different phases should be considered separately. In addition, the influences of constant and quasi-periodic forces on the predictability are different in the Lorenz system. The effect of the constant forcing on the predictability is mainly reflected in the linear phase of error growth, while the nonlinear phase should also be considered for the situation of the quasi-periodic forcing. The predictability limit of the system under constant forcing is longer than the system under quasi-periodic forcing. These results based on simple chaotic model could provide insight into the studies of the actual atmosphere predictability.

  10. Combination of external loads

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, S.; Tarp Johansen, N.J.; Joergensen, H. [Forskningscenter Risoe, Roskilde (Denmark); Gravesen, H.; Soerensen, S.L. [Carl Bro, Glostrup (Denmark); Pedersen, J. [Elsam Engineering, Fredericia (Denmark); Zorn, R.; Hvidberg Knudsen, M. [DHI Water and Environment, Hoersholm (Denmark); Voelund, P. [Energi E2, Koebenhavn (Denmark)

    2003-09-01

    The project onbectives have been: To improve and consequently opimise the basis for design of offshore wind turbines. This is done through 1) mapping the wind, wave ice and current as well as correlations of these, and 2) by clarifyring how these external conditions transform into loads. A comprehensive effort has been made to get a thorough understanding of the uncertainties that govern the reliability of wind turbines with respect to wind and wave loading. One of the conclusions is that the reliability of wind turbines is generally lower, than the average reliability of building structures that are subject not only to environmental loads, which are very uncertain, but also imposed loads and self weight, which are less uncertain than the environmental loads. The implication is that, at the moment lower load partial safety factors for onshore wind turbines cannot be recommended. For the combination of wind and wave design loads the problem is twofold: 1). A very conservative design will be generated by simply adding the individual wind and wave design loads disregarding the independence of the short-term fluctuations of wind and wave loads. 2). Characteristic values and partial safety factors for wind and wave loads are not defined similarly. This implies that the reliability levels of turbine support structures subject to purely aerodynamic loads and subject to purely hydrodynamic loads are not identical. For the problem of combining aerodynamic design loads and hydrodynamic design loads two results have been obtained in the project: 1). By simple means a site specific wave load safety factor rendering the same safety level for hydrodynamic loads as for aerodynamic loads is derived, and next, by direct square summation of extreme fluctuations, the wind and wave load safety factors are weighted. 2). Under the assumptions that a deep water site is considered and that the wave loading is a fifty-fifty mix of drag and inertia the same wind and wave load safety factor

  11. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...

  12. The External Mind

    DEFF Research Database (Denmark)

    The External Mind: an Introduction by Riccardo Fusaroli, Claudio Paolucci pp. 3-31 The sign of the Hand: Symbolic Practices and the Extended Mind by Massimiliano Cappuccio, Michael Wheeler pp. 33-55 The Overextended Mind by Shaun Gallagher pp. 57-68 The "External Mind": Semiotics, Pragmatism......, Extended Mind and Distributed Cognition by Claudio Paolucci pp. 69-96 The Social Horizon of Embodied Language and Material Symbols by Riccardo Fusaroli pp. 97-123 Semiotics and Theories of Situated/Distributed Action and Cognition: a Dialogue and Many Intersections by Tommaso Granelli pp. 125-167 Building...... Action in Public Environments with Diverse Semiotic Resources by Charles Goodwin pp. 169-182 How Marking in Dance Constitutes Thinking with the Body by David Kirsh pp. 183-214 Ambiguous Coordination: Collaboration in Informal Science Education Research by Ivan Rosero, Robert Lecusay, Michael Cole pp. 215-240...

  13. External-Memory Multimaps

    CERN Document Server

    Angelino, Elaine; Mitzenmacher, Michael; Thaler, Justin

    2011-01-01

    Many data structures support dictionaries, also known as maps or associative arrays, which store and manage a set of key-value pairs. A \\emph{multimap} is generalization that allows multiple values to be associated with the same key. For example, the inverted file data structure that is used prevalently in the infrastructure supporting search engines is a type of multimap, where words are used as keys and document pointers are used as values. We study the multimap abstract data type and how it can be implemented efficiently online in external memory frameworks, with constant expected I/O performance. The key technique used to achieve our results is a combination of cuckoo hashing using buckets that hold multiple items with a multiqueue implementation to cope with varying numbers of values per key. Our external-memory results are for the standard two-level memory model.

  14. Observation of Intrinsic Magnus Force and Direct Detection of Chirality in Superfluid 3He-A

    Science.gov (United States)

    Ikegami, Hiroki; Tsutsumi, Yasumasa; Kono, Kimitoshi

    2015-04-01

    We report details of the observation of the intrinsic Magnus (IM) force acting on negative and positive ions trapped just below a free surface of the A phase of superfluid 3He (3He-A). From the transport measurements of the ions along the surface, we found that the IM force acts on both the negative and positive ions. We also demonstrate that the transport measurements could distinguish whether the surface is composed of a chiral monodomain or multiple chiral domains. For multiple chiral domains, the current of the ions was found to be irreproducible and unstable, which was reasonably explained by the formation of the chiral domain structure and the dynamics of the chiral domain walls. For chiral monodomains, the appearance ratio of chirality emerging upon cooling through the superfluid transition temperature was found to depend on the direction of the external magnetic field, which implies the existence of an unknown coupling between the chirality and the magnetic field.

  15. Long-term Test Arrangement for Externally Strengthened Reinforced Concrete Elements

    Directory of Open Access Journals (Sweden)

    T. Vaňura

    2003-01-01

    Full Text Available Methods for external strengthening of concrete use elements of very high tensional strength glued on to its tensioned surface. These elements may be of metal, carbon fibers (CFRP, glass fibers or others, usually having very good mechanical properties. However, these high-strength elements are normally attached to concrete by epoxy resins. Epoxy resins have a low Young`s modulus and therefore a higher rate of creep may have an influence on the long-term behavior of such external strengthening. In order to verify this idea experimentally a special space-saving arrangement of tests is described in this paper. Panels act as loaded beams but simultaneously as a load for the other panels in a stand. The different load magnitude acting on a different layer of panels should make it possible to study the long-term influence of the degree of shear force on the glue creep. Certainly, the glue creep may be dependent on the type of epoxy resin; therefore several epoxy resin types are included in the tests.

  16. Magnetic force of piezo electric cantilever energy harvesting system with an externally applied magnetic field based on magnetizing current metho d%外加磁场压电悬臂梁能量采集系统的磁化电流法磁力研究∗

    Institute of Scientific and Technical Information of China (English)

    谭丹; 冷永刚; 范胜波; 高毓璣

    2015-01-01

    以外加磁场压电悬臂梁能量采集系统结构为研究对象,根据磁化电流方法探讨了具有悬臂梁特征的系统结构的磁场作用力及其计算方法,给出了相应的磁力计算模型,并将计算结果与实验数据进行了对比。研究表明,磁化电流方法导出的磁力计算模型存在偏差,其磁力计算误差随着磁铁间距缩小而增大。通过引入悬臂梁末端磁铁的偏转角度,对磁化电流法计算模型进行改进,得到合理的外加磁场压电悬臂梁能量采集系统的磁力计算模型,为该能量采集系统的进一步研究提供了可靠的磁力计算理论依据。%This paper focuses on the piezoelectric cantilever energy harvesting system with an externally applied magnetic field. The calculation method and model for the magnetic force are proposed from the magnetizing current method, and the calculation results are compared with a set of experimental data. The study shows that there is a deviation in the calculation model derived by the magnetizing current method, which increases as the distance between two magnets decreases. The calculation model is improved by introducing the deflection angle of the magnet at the end of the cantilever beam, and is reliable to calculate the magnetic force of piezoelectric cantilever energy harvesting system with an externally applied magnetic field for further studying this energy harvesting system.

  17. Hollow fiber membranes with different external corrugated surfaces for desalination by membrane distillation

    Science.gov (United States)

    García-Fernández, Loreto; García-Payo, Carmen; Khayet, Mohamed

    2017-09-01

    Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were prepared using the phase inversion spinning technique under a wet gap mode. Different corrugated outer surfaces were obtained by means of a micro-engineered spinneret, spraying the external coagulant on the nascent fiber along gap, and different spinning parameters, namely, the gap distance and the external coagulant flow rate. A quantitative evaluation of the corrugation size and shape was carried out by electron scanning microscopy and atomic force microscopy. The effect of the corrugation size and shape on the direct contact membrane distillation (DCMD) performance has been studied. The corrugated outer surface acted as micro-turbulence promoters mitigating the temperature polarization effect and enhanced the external effective surface area for condensation. Both factors improved the DCMD permeability of the hollow fiber membranes. However, corrugations with V-shaped valleys depths greater than about 30 μm did not always improve the DCMD permeate flux. It was found that the membrane prepared with the spray wetting mode exhibited the best desalination performance. The salt rejection factor of all prepared hollow fiber membranes was greater than 99.9% and the highest DCMD permeate flux of this study was greater than those reported so far for the PVDF-HFP hollow fiber membranes.

  18. Conversion of neurons and glia to external-cell fates in the external sensory organs of Drosophila hamlet mutants by a cousin-cousin cell-type respecification.

    Science.gov (United States)

    Moore, Adrian W; Roegiers, Fabrice; Jan, Lily Y; Jan, Yuh-Nung

    2004-03-15

    The Drosophila external sensory organ forms in a lineage elaborating from a single precursor cell via a stereotypical series of asymmetric divisions. HAMLET transcription factor expression demarcates the lineage branch that generates two internal cell types, the external sensory neuron and thecogen. In HAMLET mutant organs, these internal cells are converted to external cells via an unprecedented cousin-cousin cell-fate respecification event. Conversely, ectopic HAMLET expression in the external cell branch leads to internal cell production. The fate-determining signals NOTCH and PAX2 act at multiple stages of lineage elaboration and HAMLET acts to modulate their activity in a branch-specific manner.

  19. Labor Force

    Science.gov (United States)

    Occupational Outlook Quarterly, 2012

    2012-01-01

    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  20. In vivo determination of fluctuating forces during endosome trafficking using a combination of active and passive microrheology.

    Science.gov (United States)

    Robert, Damien; Nguyen, Thi-Hanh; Gallet, François; Wilhelm, Claire

    2010-04-06

    Regulation of intracellular trafficking is a central issue in cell biology. The forces acting on intracellular vesicles (endosomes) can be assessed in living cells by using a combination of active and passive microrheology. This dual approach is based on endosome labeling with magnetic nanoparticles. The resulting magnetic endosomes act both as probes that can be manipulated with external magnetic fields to infer the viscoelastic modulus of their surrounding microenvironment, and as biological vehicles that are trafficked along the microtubule network by means of forces generated by molecular motors. The intracellular viscoelastic modulus exhibits power law dependence with frequency, which is microtubule and actin-dependent. The mean square displacements of endosomes do not follow the predictions of the fluctuation-dissipation theorem, which offers evidence for active force generation. Microtubule disruption brings the intracellular medium closer to thermal equilibrium: active forces acting on the endosomes depend on microtubule-associated motors. The power spectra of these active forces, deduced through the use of a generalized Langevin equation, show a power law decrease with frequency and reveal an actin-dependent persistence of the force with time. Experimental spectra have been reproduced by a simple model consisting in a series of force steps power-law distributed in time. This model enlightens the role of the cytoskeleton dependent force exerted on endosomes to perform intracellular trafficking. In this work, the influence of cytoskeleton components and molecular motors on intracellular viscoelasticity and transport is addressed. The use of an original probe, the magnetic endosome, allows retrieving the power spectrum of active forces on these organelles thanks to interrelated active and passive measures. Finally a computational model gives estimates of the force itself and hence of the number of the motors pulling on endosomes.

  1. In vivo determination of fluctuating forces during endosome trafficking using a combination of active and passive microrheology.

    Directory of Open Access Journals (Sweden)

    Damien Robert

    Full Text Available BACKGROUND: Regulation of intracellular trafficking is a central issue in cell biology. The forces acting on intracellular vesicles (endosomes can be assessed in living cells by using a combination of active and passive microrheology. METHODOLOGY/PRINCIPAL FINDINGS: This dual approach is based on endosome labeling with magnetic nanoparticles. The resulting magnetic endosomes act both as probes that can be manipulated with external magnetic fields to infer the viscoelastic modulus of their surrounding microenvironment, and as biological vehicles that are trafficked along the microtubule network by means of forces generated by molecular motors. The intracellular viscoelastic modulus exhibits power law dependence with frequency, which is microtubule and actin-dependent. The mean square displacements of endosomes do not follow the predictions of the fluctuation-dissipation theorem, which offers evidence for active force generation. Microtubule disruption brings the intracellular medium closer to thermal equilibrium: active forces acting on the endosomes depend on microtubule-associated motors. The power spectra of these active forces, deduced through the use of a generalized Langevin equation, show a power law decrease with frequency and reveal an actin-dependent persistence of the force with time. Experimental spectra have been reproduced by a simple model consisting in a series of force steps power-law distributed in time. This model enlightens the role of the cytoskeleton dependent force exerted on endosomes to perform intracellular trafficking. CONCLUSIONS/SIGNIFICANCE: In this work, the influence of cytoskeleton components and molecular motors on intracellular viscoelasticity and transport is addressed. The use of an original probe, the magnetic endosome, allows retrieving the power spectrum of active forces on these organelles thanks to interrelated active and passive measures. Finally a computational model gives estimates of the force itself

  2. Attractive and repulsive quantum forces from dimensionality of space

    DEFF Research Database (Denmark)

    Bialynicki-Birula, I.; Cirone, M.A.; Dahl, Jens Peder

    2002-01-01

    Two particles of identical mass attract and repel each other even when there exist no classical external forces and their average relative momentum vanishes. This quantum force depends crucially on the number of dimensions of space.......Two particles of identical mass attract and repel each other even when there exist no classical external forces and their average relative momentum vanishes. This quantum force depends crucially on the number of dimensions of space....

  3. Aerodynamic forces acting on a box car running on the railway alone with the wind -break wall under strong cross -wind%强侧风不同挡风墙下棚车气动性能

    Institute of Scientific and Technical Information of China (English)

    黄尊地; 常宁

    2012-01-01

    选用车型为棚车,采用SIMPLEC算法和QUICK精度格式的数值计算方法对强侧风下不同挡风墙类型、不同路堤和挡风墙高度组合棚车的气动性能进行研究.研究结果表明:在防风效果上,土堤式挡风墙最差,加筋对拉式挡风墙相对最优;挡风墙类型为加筋对拉式,当路堤高度一定时,随着挡风墙高度的增加,棚车的倾覆方向由顺风倾覆向逆风倾覆转变;棚车在一线时,倾覆力矩转变点挡风墙的高度比在二线时高;随着路堤高度的增加,棚车倾覆力矩转变点挡风墙的高度逐渐减小,但减小的幅值变小.研究结论为既有线挡风墙优化建造提供理论依据.%Based on the box car, a simulation method with SIMPLEC arithmetic and QUICK precision format was used in the research of the aerodynamic forces acting on a box car running on the railway along with the different wind - break wall under strong cross - wind. The results show that in the wind - break effect, the embankment wind - break wall is the worst of all, the tendon wind - break wall is the best of all; when the height of the embankment is constant for the tendon wind - break wall, with the increas of the height of the wind - break wall, the overturning moment of the box car will change from down the wind to headwind; when the overturning moment is 0, the relevant height of the wind - break wall on the first railway is higher than that on the second; when the height of the embankment increases, the relevant height is decrease, but the extent becomes small. The conclusions provide a reliable theoretical basis for optimization and construction of the wind -break wall on the existing railway from Lanchow to Urumqi.

  4. Analysis of forces acting on bottom outlet structure and measures for tensile stress on upstream dam surface%导流底孔结构受力分析与坝上游面拉应力控制措施

    Institute of Scientific and Technical Information of China (English)

    程宵; 苏凯; 伍鹤皋

    2011-01-01

    Based on a bottom outlet project, with regard to the characteristics of forces acting on the structure during the blocking period, the stress distributions of the structure and upstream dam surface were studied by means of the 3D finite element method. The results show that a wide range of tensile stress along the dam axis will appear at the upstream dam surface when the position of the seam which links the orifice of the bottom outlet and the dam is arranged in front of the upstream dam surface. In order to reduce the tensile stress along the dam axis efficiently, measures of filling materials in the seams at both sides of the dam or moving the position of the seam which links the orifice and the dam to the parallel position of the upstream dam surface should be taken. In this way, the possibility of concrete crack on the upstream dam surface during the construction, operation and blocking periods may be reduced.%结合某导流底孔工程,针对封堵期结构的受力特征,采用三维有限单元法对导流底孔坝段结构和坝上游面的应力分布情况进行计算分析.结果表明:导流底孔进水口段和坝内孔身段的分缝布置于坝面上游时,坝上游面将出现较大范围的横河向拉应力,当考虑大坝两侧分缝内填充材料作用或将导流底孔进水口段与坝内孔身段的分缝位置下移至与大坝上游面平齐时,能够有效地减小坝上游面拉应力的数值与范围,降低坝上游面混凝土受拉开裂的可能性.

  5. A Mechanism of ELM Mitigation by External Magnetic Field Perturbations

    Science.gov (United States)

    Singh, Raghvendra; Jhang, H.; Kim, J.-H.; Hahm, T. S.

    2016-10-01

    We study the impact of external magnetic perturbations (EMP) on the stability of ballooning mode (BM). We use: 1) the two-step process; 2) standard four wave interactions. In two-step process, we consider EMP are long wave-length perturbations interacting with short scale BM and generating side-bands of higher harmonics. This calculates contributions from all the high toroidal mode numbers. EMP can modify the dispersion characteristics of BM - the growth spectrum becomes broader in kBM space. The increase in high kBM can lead to the mitigation of an ELM crash by increasing turbulent transport. New nonlinear instability is also found even below the BM threshold at large EMP amplitude. In four wave interaction, EMP act like a short scale pump wave interacting with BM and creating two sidebands. The side-bands couple with the pump and produce the ponderomotive force, magnetic stress at BM frequency. EMP may enhance the BM instability threshold if RMP K->BM RMP and reduce the threshold if K->BM >K->RMP .

  6. Regularization by External Variables

    DEFF Research Database (Denmark)

    Bossolini, Elena; Edwards, R.; Glendinning, P. A.

    2016-01-01

    Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind of regula...... of regularization, by external variables that shadow either the state or the switch of the original system. The shadow systems are derived from and inspired by various applications in electronic control, predator-prey preference, time delay, and genetic regulation....

  7. External Costs as Driving Forces of Land Use Changes

    Directory of Open Access Journals (Sweden)

    Dirk Loehr

    2010-04-01

    Full Text Available Land conversion is often not carried out in a sustainable way. The loss of arable land and biodiversity, concern about food security and rising costs of infrastructure due to urban sprawl are just some of the problems under discussion. This paper compares Germany, China and Cambodia. The article points out that, despite huge differences in institutions and governance, unsustainable land use changes mostly have some patterns in common: The beneficiaries of land conversion are often well-organized actors, whereas the costs of land conversion are often shifted to poorly organized groups and to society as a whole. A sustainable land use policy has to look for a better coupling of benefits and costs of land use changes. In order to achieve this goal, the article suggests completing the planning law with a suitable economic framework.

  8. Balancing Acts

    Science.gov (United States)

    ... Past Issues Special Section: Focus on Communication Balancing Acts Past Issues / Fall 2008 Table of Contents For ... scientific research on hearing, balance, smell, taste, voice, speech, and language—common elements in how we perceive ...

  9. Force approach to radiation reaction

    Energy Technology Data Exchange (ETDEWEB)

    López, Gustavo V., E-mail: gulopez@udgserv.cencar.udg.mx

    2016-02-15

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  10. Force approach to radiation reaction

    Science.gov (United States)

    López, Gustavo V.

    2016-02-01

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  11. Dispersion Forces

    CERN Document Server

    Buhmann, Stefan Yoshi

    2012-01-01

    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  12. Exact results for the behavior of the thermodynamic Casimir force in a model with a strong adsorption

    Science.gov (United States)

    Dantchev, Daniel M.; Vassilev, Vassil M.; Djondjorov, Peter A.

    2016-09-01

    When massless excitations are limited or modified by the presence of material bodies one observes a force acting between them generally called Casimir force. Such excitations are present in any fluid system close to its true bulk critical point. We derive exact analytical results for both the temperature and external ordering field behavior of the thermodynamic Casimir force within the mean-field Ginzburg-Landau Ising type model of a simple fluid or binary liquid mixture. We investigate the case when under a film geometry the boundaries of the system exhibit strong adsorption onto one of the phases (components) of the system. We present analytical and numerical results for the (temperature-field) relief map of the force in both the critical region of the film close to its finite-size or bulk critical points as well as in the capillary condensation regime below but close to the finite-size critical point.

  13. Glycoprotein Ib-IX-V Complex Transmits Cytoskeletal Forces That Enhance Platelet Adhesion.

    Science.gov (United States)

    Feghhi, Shirin; Munday, Adam D; Tooley, Wes W; Rajsekar, Shreya; Fura, Adriane M; Kulman, John D; López, Jose A; Sniadecki, Nathan J

    2016-08-09

    Platelets bind to exposed vascular matrix at a wound site through a highly specialized surface receptor, glycoprotein (GP) Ib-IX-V complex, which recognizes von Willebrand factor (VWF) in the matrix. GPIb-IX-V is a catch bond for it becomes more stable as force is applied to it. After attaching to the wound site, platelets generate cytoskeletal forces to compact and reinforce the hemostatic plug. Here, we evaluated the role of the GPIb-IX-V complex in the transmission of cytoskeletal forces. We used arrays of flexible, silicone nanoposts to measure the contractility of individual platelets on VWF. We found that a significant proportion of cytoskeletal forces were transmitted to VWF through GPIb-IX-V, an unexpected finding given the widely held notion that platelet forces are transmitted exclusively through its integrins. In particular, we found that the interaction between GPIbα and the A1 domain of VWF mediates this force transmission. We also demonstrate that the binding interaction between GPIbα and filamin A is involved in force transmission. Furthermore, our studies suggest that cytoskeletal forces acting through GPIbα are involved in maintaining platelet adhesion when external forces are absent. Thus, the GPIb-IX-V/VWF bond is able to transmit force, and uses this force to strengthen the bond through a catch-bond mechanism. This finding expands our understanding of how platelets attach to sites of vascular injury, describing a new, to the best of our knowledge, mechanism in which the catch bonds of GPIb-IX-V/VWF can be supported by internal forces produced by cytoskeletal tension.

  14. The destabilizing effect of external damping: Singular utter boundary for the Pfluger column with vanishing external dissipation

    CERN Document Server

    Tommasini, Mirko; Misseroni, Diego; Bigoni, Davide

    2016-01-01

    Elastic structures loaded by nonconservative positional forces are prone to instabilities induced by dissipation: it is well-known in fact that internal viscous damping destabilizes the marginally stable Ziegler's pendulum and Pfluger column (of which the Beck's column is a special case), two structures loaded by a tangential follower force. The result is the so-called 'destabilization paradox', where the critical force for flutter instability decreases by an order of magnitude when the coefficient of internal damping becomes infinitesimally small. Until now external damping, such as that related to air drag, is believed to provide only a stabilizing effect, as one would intuitively expect. Contrary to this belief, it will be shown that the effect of external damping is qualitatively the same as the effect of internal damping, yielding a pronounced destabilization paradox. Previous results relative to destabilization by external damping of the Ziegler's and Pfluger's elastic structures are corrected in a defi...

  15. Molecular Dynamics Simulations of a Linear Nanomotor Driven by Thermophoretic Forces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

    ,7,8,9 Nanomotors are an attractive goal for nanotechnology.9-13 Such nano-scale structures capable of converting thermal energy into work will be needed in many types of nanodevices, including nanoconveyors14, memory devices15 and nano-encapsulated material delivery systems16,17. Moreover to design and manufacture...... future molecular machines a complete understanding of the friction forces involved on the transport process at the molecular level have to be addressed.18 In this work we perform Molecular Dynamics (MD) simulations using the MD package FASTTUBE19 to study a molecular linear motor consisting of coaxial...... of the capsule is driven by thermophoresis we perform additional simulations in order to study the friction and thermophoretic forces acting on the inner CNT. In these simulations, we constrain the velocity of center of mass of the inner CNT and extract from the simulations the external forces required to drive...

  16. A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses

    Directory of Open Access Journals (Sweden)

    Edith M. Sevick

    2013-10-01

    Full Text Available We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle interactions with the mobile rings, so that one section is of high energy (repulsive for the rings and another section is of lower energy (or attractive. This kind of rotaxane can exhibit rapid changes in displacement or force, and in particular, this molecule can exhibit a yield stress in which the piston suddenly compresses under a small increase in the applied force.

  17. Design of a compact six-component force and moment sensor for aerodynamic testing

    Directory of Open Access Journals (Sweden)

    Georgeta IONAŞCU

    2011-03-01

    Full Text Available The measurement of steady and fluctuating forces acting on a body in a flow is one of themain tasks in wind-tunnel experiments. Usually, a multi-component strain gauge force and momentsensor (also known as balance is used to generate signals which are processed by means of anadequate instrumentation.To design a wind-tunnel balance, the specifications of the load ranges and the available space (for theplacement of the balance inside or outside the model are required. The main challenge is to conceivethe elastic element of the sensor as a monolithic part with a relative simple geometry and to identifythe adequate placement of strain gauges to maximize the measuring sensitivities and to diminish theinter-influence of the components.This paper describes the design of a six-component force/moment sensor which is compact, has highmeasuring sensitivities, and can be used either as internal or as external balance in the aerodynamictesting.

  18. 78 FR 74122 - Privacy Act of 1974; System of Records

    Science.gov (United States)

    2013-12-10

    ... Department of the Air Force Privacy Act of 1974; System of Records AGENCY: Department of the Air Force, DoD... inventory of records systems subject to the Privacy Act of 1974, as amended. This system will be used to... notices for systems of records subject to the Privacy Act of 1974 (5 U.S.C. 552a(r)), as amended,...

  19. Feasibility design of a floating airport and estimation of environmental forces on it; Futaishiki kuko no sekkei to kankyo gairyoku no suitei ni kansuru kento

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Y.; Tabeta, S.; Takei, Y. [Yokohama National University, Yokohama (Japan). Faculty of Engineering

    1996-12-31

    A rough design was performed on a floating airport. On this floating structure, environmental external force was estimated, mooring design was carried out, and discussions was given on the position retaining performance important for airport functions and behavior of the floating structure. The discussion was given on cases that the airport is surrounded and not surrounded by floating breakwaters. A floating structure which becomes super-large in size requires considerations on force due to sea level gradient as a result of a tide. Deriving flow condition changes and force acting on the floating structure simultaneously by using numerical calculations makes it possible to estimate current force given with considerations on influence of the flow conditions created by installing the floating airport. Estimation was carried out by using a zone dividing method on wave drifting force acting upon the floating airport. As a result, it was found that installing floating and permeating type breakwaters can reduce the wave drifting force acting on the floating airport. The wave drifting force working on the floating airport can be reduced by installing the floating and permeating type breakwaters to lower levels than when no such breakwaters are installed. The airport may be moored with less number of fenders when the fenders of the same type are used. 18 refs., 10 figs., 5 tabs.

  20. Quantum mechanics in strong time dependent external fields

    Energy Technology Data Exchange (ETDEWEB)

    Pomeau, Y.

    1986-01-01

    In quantum mechanics, time dependent Hamiltonians are most often studied by perturbation methods, the amplitude of the unsteady force being assumed to be small. On two examples (two level system with a large time dependent coupling, and atoms in large external unsteady field). I show that the opposite limit (large time dependent field) can be analyzed in some details too. For a particle in a central potential and submitted to a large periodic external field, one is led to make a Kapitza averaging because the intrinsic frequency tends to zero when the external field diverges. In that way one has to introduce a steady effective potential with singular turning points.

  1. Wind Forces on Container Ships

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent

    2012-01-01

    An investigation of the wind forces acting on a 9,000+ TEU container ship has been carried out through a series of wind tunnel tests. It was investigated how the wind forces depend on the container configuration on the deck using a 1:450 scale model and a series of appropriate container...... are presented as nondimensional coefficients. It is concluded, that the measured forces and moment depend on the container configuration on deck, and the results may provide a general idea of how the magnitude of the wind forces is affected by a given container stacking configuration on a similar container ship....

  2. Ultrasensitive hysteretic force sensing with parametric nonlinear oscillators

    Science.gov (United States)

    Papariello, Luca; Zilberberg, Oded; Eichler, Alexander; Chitra, R.

    2016-08-01

    We propose a method for linear detection of weak forces using parametrically driven nonlinear resonators. The method is based on a peculiar feature in the response of the resonator to a near resonant periodic external force. This feature stems from a complex interplay among the parametric drive, external force, and nonlinearities. For weak parametric drive, the response exhibits the standard Duffing-like single jump hysteresis. For stronger drive amplitudes, we find a qualitatively new double jump hysteresis which arises from stable solutions generated by the cubic Duffing nonlinearity. The additional jump exists only if the external force is present and the frequency at which it occurs depends linearly on the amplitude of the external force, permitting a straightforward ultrasensitive detection of weak forces. With state-of-the-art nanomechanical resonators, our scheme should permit force detection in the attonewton range.

  3. External Measures of Cognition

    Directory of Open Access Journals (Sweden)

    Osvaldo eCairo

    2011-10-01

    Full Text Available The human brain is undoubtedly the most impressive, complex and intricate organ that has evolved over time. It is also probably the least understood, and for that reason, the one that is currently attracting the most attention. In fact, the number of comparative analyses that focus on the evolution of brain size in Homo sapiens and other species has increased dramatically in recent years. In neuroscience, no other issue has generated so much interest and been the topic of so many heated debates as the difference in brain size between socially defined population groups, both its connotations and implications. For over a century, external measures of cognition have been related to intelligence. However, it is still unclear whether these measures actually correspond to cognitive abilities. In summary, this paper must be reviewed with this premise in mind.

  4. Capsules with external navigation and triggered release.

    Science.gov (United States)

    Shchukin, Dmitry G; Shchukina, Elena

    2014-10-01

    Encapsulation is an important technology for pharmaceutical industry, food production, et cetera. Its current level of development requires capsule functionalization. One of the interesting ideas to provide new functionality to the microcapsule and nanocapsule is layer-by-layer deposition of functional species. This technique provides step-by-step adsorption of various species (polyelectrolytes, nanoparticles, proteins) when the layer growth is controlled by electrostatic, hydrogen bonding, hydrophobic forces and forming multilayer shells with nanometer precision. This review article introduces recent achievements of layer-by-layer technique attaining external navigation ability and release properties the capsule shell.

  5. The forced vibrations of three-layer orthotropic plate at incomplete contact between bottom layers

    Directory of Open Access Journals (Sweden)

    Aghalovyan L. A.

    2007-09-01

    Full Text Available The three-dimensional dynamic problem of the elasticity theory on forced vibration of orthotropic plate at incomplete contact between bottom layers and at full contact between the top layers is solved by the asymptotic method. The bottom obverse surface is subject to external dynamic influences, and top - is rigidly fixed. The common asymptotic solution of the problem is found. The closed solution for particular type of problems is found. It is known, that constant tangential displacements acting to the third layer do not influence in stress-strain state of the first and second layer. The resonance arising conditions are established.

  6. On population resilience to external perturbations

    CERN Document Server

    Roques, Lionel

    2010-01-01

    We study a spatially explicit harvesting model in periodic or bounded environments. The model is governed by a parabolic equation with a spatially dependent nonlinearity of Kolmogorov--Petrovsky--Piskunov type, and a negative external forcing term $-\\delta$. Using sub- and supersolution methods and the characterization of the first eigenvalue of some linear elliptic operators, we obtain existence and nonexistence results as well as results on the number of stationary solutions. We also characterize the asymptotic behavior of the evolution equation as a function of the forcing term amplitude. In particular, we define two critical values $\\delta^*$ and $\\delta_2$ such that, if $\\delta$ is smaller than $\\delta^*$, the population density converges to a "significant" state, which is everywhere above a certain small threshold, whereas if $\\delta$ is larger than $\\delta_2$, the population density converges to a "remnant" state, everywhere below this small threshold. Our results are shown to be useful for studying th...

  7. Stochastic Forcing for Ocean Uncertainty Prediction

    Science.gov (United States)

    2013-09-30

    shallow water waves governed by Korteweg-de Vries ( KdV ) dynamics with stochastic forcing. Uncertain Boundary Conditions and DO Equations: A...schemes to time-integrate shallow water surface waves governed by KdV equations with external stochastic forcing. We find that the DO scheme is

  8. Entropic forces in Brownian motion

    CERN Document Server

    Roos, Nico

    2013-01-01

    The interest in the concept of entropic forces has risen considerably since E. Verlinde proposed to interpret the force in Newton s second law and Gravity as entropic forces. Brownian motion, the motion of a small particle (pollen) driven by random impulses from the surrounding molecules, may be the first example of a stochastic process in which such forces are expected to emerge. In this note it is shown that at least two types of entropic motion can be identified in the case of 3D Brownian motion (or random walk). This yields simple derivations of known results of Brownian motion, Hook s law and, applying an external (nonradial) force, Curie s law and the Langevin-Debye equation.

  9. Magnus force in superfluids and superconductors

    Science.gov (United States)

    Sonin, E. B.

    1997-01-01

    The forces on the vortex, transverse to its velocity, are considered. In addition to the superfluid Magnus force from the condensate (superfluid component), there are transverse forces from thermal quasiparticles and external fields violating the Galilean invariance. The forces between quasiparticles and the vortex originate from interference of quasiparticles with trajectories on the left and on the right from the vortex like similar forces for electrons interacting with the thin magnetic-flux tube (the Aharonov-Bohm effect). These forces are derived for phonons from the equations of superfluid hydrodynamics, and for BCS quasiparticles from the Bogolyubov-de Gennes equations. The effect of external fields breaking Galilean invariance is analyzed for vortices in the two-dimensional Josephson junction array. The symmetry analysis of the classical equations for the array shows that the total transverse force on the vortex vanishes. Therefore the Hall effect which is linear in the transverse force is absent also. This means that the Magnus force from the superfluid component exactly cancels with the transverse force from the external fields. The results of other approaches are also brought together for discussion.

  10. Strong Force

    CERN Document Server

    Without the strong force, there could be no life. The carbon in living matter is synthesised in stars via the strong force. Lighter atomic nuclei become bound together in a process called nuclear fusion. A minor change in this interaction would make life impossible. As its name suggests, the strong force is the most powerful of the 4 forces, yet its sphere of influence is limited to within the atomic nucleus. Indeed it is the strong force that holds together the quarks inside the positively charged protons. Without this glue, the quarks would fly apart repulsed by electromagnetism. In fact, it is impossible to separate 2 quarks : so much energy is needed, that a second pair of quarks is produced. Text for the interactive: Can you pull apart the quarks inside a proton?

  11. External fixators in haemophilia.

    Science.gov (United States)

    Lee, V; Srivastava, A; PalaniKumar, C; Daniel, A J; Mathews, V; Babu, N; Chandy, M; Sundararaj, G D

    2004-01-01

    External fixators (EF) are not commonly used for patients with haemophilia. We describe the use of EF (Ilizarov, AO- uni- and bi-planar fixators and Charnley clamp) in nine patients (mean age: 19.2 years; range: 9-37) with haemophilia for the following indications - arthrodesis of infected joints, treatment of open fractures and osteoclasis. EF required an average of nine skin punctures [range: 4-17 were maintained for a period of 15 weeks (range: 8-29.5), without regular factor replacement, till bone healing was adequate and were removed with a single dose of factor infusion]. The mean preoperative factor level achieved was 85% (range: 64-102%). Much lower levels were subsequently maintained till wound healing. The average total factor consumption was 430 IU kg(-1) (range: 240-870), administered over a period of 17 days (range: 9-44). There were no major complications related to EF except in a patient who developed inhibitors. In conclusion, EF can be used safely in haemophilic patients who do not have inhibitors and does not require prolonged factor replacement.

  12. The role of magnetoplasmons in Casimir force calculations

    CERN Document Server

    Esquivel-Sirvent, R; Palomino-Ovando, M A; Cocoletzi, G H

    2009-01-01

    In this paper we review the role of magneto plasmon polaritons in the Casimir force calculations. By applying an external constant magnetic field a strong optical anisotropy is induced on two parallel slabs reducing the reflectivity and thus the Casimir force. As the external magnetic field increases, the Casimir force decreases. Thus, with an an external magnetic field the Casimir force can be controlled.The calculations are done in the Voigt configuration where the magnetic field is parallel to the slabs. In this configuration the reflection coefficients for TE and TM modes do not show mode conversion.

  13. Attentional Focusing Instructions and Force Production

    Directory of Open Access Journals (Sweden)

    David C Marchant

    2011-01-01

    Full Text Available Research progress assessing the role of attentional focusing instructions on skill acquisition and performance has lead researchers to apply this approach to force production tasks. Initial converging evidence indicates that force production tasks are sensitive to verbal instruction; externally focused instructions (onto movement outcomes, or onto the object force is being exerted against are shown to be more beneficial than internally focused instructions (focusing attention onto the movements being executed. These benefits are observed for maximal and accurate force production, as well as the maintenance of force production in prolonged tasks. A range of mechanisms are identified supporting the proposal that an external focus promotes movement efficiency in line with energy and effort conservation. Future research is required to assess how this developing body of work interacts with the broader understanding of psychological and physiological factors implicated in the effective production, maintenance and limitation of maximal or sub-maximal forces.

  14. 78 FR 28895 - Sunshine Act Meetings

    Science.gov (United States)

    2013-05-16

    ... Task Force (Resolution 2013-XXX) 4. Consider and act on whether to authorize an executive session of... Vice President for Legal Affairs, General Counsel, and Corporate Secretary (Resolution 2013-XXX) 7...

  15. Skepticism, contextualism, externalism and modality

    National Research Council Canada - National Science Library

    Ron Wilburn

    2006-01-01

    .... However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated...

  16. Markets, Herding and Response to External Information.

    Science.gov (United States)

    Carro, Adrián; Toral, Raúl; San Miguel, Maxi

    2015-01-01

    We focus on the influence of external sources of information upon financial markets. In particular, we develop a stochastic agent-based market model characterized by a certain herding behavior as well as allowing traders to be influenced by an external dynamic signal of information. This signal can be interpreted as a time-varying advertising, public perception or rumor, in favor or against one of two possible trading behaviors, thus breaking the symmetry of the system and acting as a continuously varying exogenous shock. As an illustration, we use a well-known German Indicator of Economic Sentiment as information input and compare our results with Germany's leading stock market index, the DAX, in order to calibrate some of the model parameters. We study the conditions for the ensemble of agents to more accurately follow the information input signal. The response of the system to the external information is maximal for an intermediate range of values of a market parameter, suggesting the existence of three different market regimes: amplification, precise assimilation and undervaluation of incoming information.

  17. Markets, Herding and Response to External Information.

    Directory of Open Access Journals (Sweden)

    Adrián Carro

    Full Text Available We focus on the influence of external sources of information upon financial markets. In particular, we develop a stochastic agent-based market model characterized by a certain herding behavior as well as allowing traders to be influenced by an external dynamic signal of information. This signal can be interpreted as a time-varying advertising, public perception or rumor, in favor or against one of two possible trading behaviors, thus breaking the symmetry of the system and acting as a continuously varying exogenous shock. As an illustration, we use a well-known German Indicator of Economic Sentiment as information input and compare our results with Germany's leading stock market index, the DAX, in order to calibrate some of the model parameters. We study the conditions for the ensemble of agents to more accurately follow the information input signal. The response of the system to the external information is maximal for an intermediate range of values of a market parameter, suggesting the existence of three different market regimes: amplification, precise assimilation and undervaluation of incoming information.

  18. Markets, Herding and Response to External Information

    Science.gov (United States)

    Carro, Adrián; Toral, Raúl; San Miguel, Maxi

    2015-01-01

    We focus on the influence of external sources of information upon financial markets. In particular, we develop a stochastic agent-based market model characterized by a certain herding behavior as well as allowing traders to be influenced by an external dynamic signal of information. This signal can be interpreted as a time-varying advertising, public perception or rumor, in favor or against one of two possible trading behaviors, thus breaking the symmetry of the system and acting as a continuously varying exogenous shock. As an illustration, we use a well-known German Indicator of Economic Sentiment as information input and compare our results with Germany’s leading stock market index, the DAX, in order to calibrate some of the model parameters. We study the conditions for the ensemble of agents to more accurately follow the information input signal. The response of the system to the external information is maximal for an intermediate range of values of a market parameter, suggesting the existence of three different market regimes: amplification, precise assimilation and undervaluation of incoming information. PMID:26204451

  19. External Influences on an Internal Process: Supporting Preservice Teacher Research

    Science.gov (United States)

    Schulte, Ann; Klipfel, Lyndsay Halpin

    2016-01-01

    In an effort to better understand how participating in teacher research as a student teacher compares to conducting it as a practicing teacher, a teacher educator and her former teacher education student engaged in a collaborative dialogue. They focus their reflections in this article on the impact of external forces on the process of teacher…

  20. Weak Force

    CERN Multimedia

    Without the weak force, the sun wouldn't shine. The weak force causes beta decay, a form of radioactivity that triggers nuclear fusion in the heart of the sun. The weak force is unlike other forces: it is characterised by disintegration. In beta decay, a down quark transforms into an up quark and an electron is emitted. Some materials are more radioactive than others because the delicate balance between the strong force and the weak force varies depending on the number of particles in the atomic nucleus. We live in the midst of a natural radioactive background that varies from region to region. For example, in Cornwall where there is a lot of granite, levels of background radiation are much higher than in the Geneva region. Text for the interactive: Move the Geiger counter to find out which samples are radioactive - you may be surprised. It is the weak force that is responsible for the Beta radioactivity here. The electrons emitted do not cross the plastic cover. Why do you think there is some detected radioa...

  1. International labor migration and external debt.

    Science.gov (United States)

    Bustamante, J A

    1987-01-01

    The prevailing Mexican and US definitions of undocumented migration are poles apart. The US views it as a criminal problem. Mexicans view the undocumented migrants as actors in an economic game in which the rules are extremely disadvantageous to these migrants. Migrants themselves and their communities view the undocumented as a positive element. It is necessary to move toward a bilateral focus and bilateral negotiation on the issue of migratory workers. This proposal derives from several assumptions: 1) the external debt is a bilateral or multilateral issue, 2) it is important to avoid forcing debtor countries to choose between stimulating economic growth or making payment on their foreign debt, 3) prevailing public opinion in the US favors halting undocumented migration, 4) the US views the migration of undocumented Mexicans as the result of forces endogenous to Mexico and exogenous to the US, 5) the US views both Mexico's ability to make payment on its external debt and to halt emigration as tied to the Mexican government's ability or inability to reconcile political stability with scarce monetary resources, and 6) political instability in Mexico could augment emigration to the US and undermine Mexico's ability to address its foreign debt. The following proposal suggests means to link negotiation on the external debt to that of undocumented migration: 1) The Mexican government could reach an accord with the US to channel a portion of the actual interest on the external debt as a fund to be invested in Mexico to construct a system of labor intensive agroindustrial productive units designed to attract former or potential migratory workers; 2) the total amount of these funds would be deducted from interest payments on the principal of the actual external debt and redefined as an ad hoc loan to Mexico to finance these production units; 3) part of the production from these units would be incorporated into ongoing US food relief and food assistance programs; 4) the

  2. Origin of Knudsen forces on heated microbeams

    KAUST Repository

    Zhu, Taishan

    2010-09-09

    The presented work probes the fundamentals of Knudsen forces. Using the direct simulation Monte Carlo (DSMC) method, the flows induced by temperature inhomogeneity within a representative configuration and the Knudsen force acting on a heated microbeam are captured as functions of Knudsen number in the entire flow regime. Both flow strength and Knudsen force peak in the transition regime and negative Knudsen force absent in experimental data is observed. The mechanisms of the thermally induced flows and Knudsen forces are studied. It has been found that thermal edge flow is the main driven source for the formation of the Knudsen force on microbeams and domain configuration plays an important role in the process.

  3. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...... how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area...

  4. ExternE transport methodology for external cost evaluation of air pollution (DK)

    Energy Technology Data Exchange (ETDEWEB)

    Solvang Jensen, S.; Berkowicz, R.; Brandt, J. [National Environmental Research Inst., Dept. of Atmospheric Environment (Denmark); Willumsen, E.; Kristensen, N.B. [COWI (Denmark)

    2004-07-01

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AiGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Inititally, a brief description of the ExternE Transport methodology is given and it is summarised how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area. (au)

  5. External coating of colonic anastomoses

    DEFF Research Database (Denmark)

    Pommergaard, Hans-Christian; Achiam, Michael Patrick; Rosenberg, Jacob

    2012-01-01

    Colon anastomotic leakage remains both a frequent and serious complication in gastrointestinal surgery. External coating of colonic anastomoses has been proposed as a means to lower the rate of this complication. The aim of this review was to evaluate existing studies on external coating of colonic...

  6. Retrofitting Systems for External Walls

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report, 9 different external and internal retrofitting systems are analyzed using numerical calculations. The analysis focuses on the thermal bridge effects in the different systems, and on this basis it is discussed whether internal or external retrofitting has the most advantages...

  7. Comprehensive Employment and Training Act. Hearing before the Task Force on Human Resources of the Committee on the Budget, House of Representatives, Ninety-Fifth Congress, First Session (June 30, 1977)

    Science.gov (United States)

    Congress of the U.S., Washington, DC. House Committee on the Budget.

    Testimonies addressing the implementation of new federal employment training programs and the expanded Comprehensive Employment and Training Act (CETA) programs, the practicality of forward funding, and the relationship of CETA to welfare reform are presented in this hearing record. Statements by representatives of the Department of Labor, the…

  8. Air classifier technology (ACT) in dry powder inhalation. Part 1 : Introduction of a novel force distribution concept (FDC) explaining the performance of a basic air classifier on adhesive mixtures

    NARCIS (Netherlands)

    de Boer, A H; Hagedoorn, P; Gjaltema, D; Goede, J; Frijlink, H W

    2003-01-01

    Air classifier technology (ACT) is introduced as part of formulation integrated dry powder inhaler development (FIDPI) to optimise the de-agglomeration of inhalation powders. Carrier retention and de-agglomeration results obtained with a basic classifier concept are discussed. The theoretical cut-of

  9. Maximal loads acting on legs of powered roof support unit in longwalls with bumping hazards

    Institute of Scientific and Technical Information of China (English)

    StanislawSzweda

    2001-01-01

    In the article the results of measurements of the resultant force in the legs of a powered roof support unit, caused by a dynamic interaction bf the rock mass, are discussed. The measurements have been taken in the Iongwalls mined with a roof fall, characterized by the highest degree of bumping hazard. It has been stated that the maximal force in the legs Fro, recorded during a dynamic interaction of the rock mass, is proportional to the initial static force in the legs Fst.p Therefore a need for a careful selection of the initial load of the powered roof support, according to the local mining and geological conditions, results from such a statement. Setting the legs with the supporting load exceeding the indispensable value for keeping the direct roof solids in balance, deteriorating the operational parameters of a Iongwall system also has a disadvantageous influence on the value of the force in the legs and the rate of its increase, caused by a dynamic interaction of the rock mass. A correct selection of the initial load causes a decrease in the intensity of a dynamic interaction of the rock mass on powered roof supports, which also has an advanta igeous influence on their life, Simultaneously with the measurements of the resultant force in the legs, the vertical acceleration of the canopy was also recorded. It has enabled to prove that the external dynamic forces may act on the unit both from the roof as well as from the floor. The changes of the force in the legs caused by dynamic phenomena intrinsically created in the roof and changes of the force in the legs caused by blasting explosives in the roof of the working, have been analyzed separately. It has been stated that an increase in the loads of legs, caused by intrinsic phenomena is significantly higher than a force increase in the legs caused by blasting. It means that powered roof supports, to be operated in the workings, where the bumping hazard occurs, will also transmit the loads acting on a unit

  10. Buckling of elliptical rings under uniform external pressure

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Y.

    1991-04-03

    A thin, elastic elliptical ring is subjected to uniform external pressure. The lowest critical pressure is computed and presented for various ratio of the major axis to the minor axis of the elliptical ring. It is found that the critical pressure for an elliptical ring is higher than that for the circular ring whose diameter is equal to the major axis of the elliptical ring. It can be shown that under the same external pressure, the axial force developed in the elliptical ring is less than that developed in the corresponding circular ring. Thus, a higher pressure is required to buckle the elliptical rings. Therefore, by changing the shape of the ring from circular to elliptical, the capability of the ring to sustain the external pressure can be increased substantially. The results of this study can be useful in the design of elliptical reinforcing rings and thin-walled tubes subjected to external pressure.

  11. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    Research on relative performance measures, transfer pricing, beyond budgeting initiatives, target costing, piece rates systems and value based management has for decades underlined the importance of external benchmarking in performance management. Research conceptualises external benchmarking...... the conditions upon which the market mechanism is performing within organizations. This paper aims to contribute to research by providing more insight to the conditions for the use of external benchmarking as an element in performance management in organizations. Our study explores a particular type of external...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  12. iCub Whole-body Control through Force Regulation on Rigid Noncoplanar Contacts

    Directory of Open Access Journals (Sweden)

    Francesco eNori

    2015-03-01

    Full Text Available This paper details the implementation on the humanoid robot iCub of state-of-the-art algorithms for whole-body control. We regulate the forces between the robot and its surrounding environment to stabilize a desired robot posture. We assume that the forces and torques are exerted on rigid contacts. The validity of this assumption is guaranteed by constraining the contact forces and torques, e.g. the contact forces must belong to the associated friction cones. The implementation of this control strategy requires to estimate the external forces acting on the robot, and the internal joint torques. We then detail algorithms to obtain these estimations when using a robot with an iCub-like sensor set, i.e. distributed six-axis force-torque sensors and whole-body tactile sensors. A general theory for identifying the robot inertial parameters is also presented. From an actuation standpoint, we show how to implement a joint torque control in the case of DC brushless motors. In addition, the coupling mechanism of the iCub torso is investigated. The soundness of the entire control architecture is validated in a real scenario involving the robot iCub balancing and making contacts at both arms.

  13. Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.

    Science.gov (United States)

    Ei Ei, Htwe; Nakama, Yuhi; Tanaka, Hiroshi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi

    2016-11-01

    The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials.

  14. Charge-Spot Model for Electrostatic Forces in Simulation of Fine Particulates

    Science.gov (United States)

    Walton, Otis R.; Johnson, Scott M.

    2010-01-01

    The charge-spot technique for modeling the static electric forces acting between charged fine particles entails treating electric charges on individual particles as small sets of discrete point charges, located near their surfaces. This is in contrast to existing models, which assume a single charge per particle. The charge-spot technique more accurately describes the forces, torques, and moments that act on triboelectrically charged particles, especially image-charge forces acting near conducting surfaces. The discrete element method (DEM) simulation uses a truncation range to limit the number of near-neighbor charge spots via a shifted and truncated potential Coulomb interaction. The model can be readily adapted to account for induced dipoles in uncharged particles (and thus dielectrophoretic forces) by allowing two charge spots of opposite signs to be created in response to an external electric field. To account for virtual overlap during contacts, the model can be set to automatically scale down the effective charge in proportion to the amount of virtual overlap of the charge spots. This can be accomplished by mimicking the behavior of two real overlapping spherical charge clouds, or with other approximate forms. The charge-spot method much more closely resembles real non-uniform surface charge distributions that result from tribocharging than simpler approaches, which just assign a single total charge to a particle. With the charge-spot model, a single particle may have a zero net charge, but still have both positive and negative charge spots, which could produce substantial forces on the particle when it is close to other charges, when it is in an external electric field, or when near a conducting surface. Since the charge-spot model can contain any number of charges per particle, can be used with only one or two charge spots per particle for simulating charging from solar wind bombardment, or with several charge spots for simulating triboelectric charging

  15. Measuring the Magnetic Force on a Current-Carrying Conductor.

    Science.gov (United States)

    Herreman, W.; Huysentruyt, R.

    1995-01-01

    Describes a fast and simple method for measuring the magnetic force acting on a current-carrying conductor using a digital balance. Discusses the influence of current intensity and wire length on the magnetic force on the conductor. (JRH)

  16. Forced Snaking

    Science.gov (United States)

    Ponedel, Benjamin; Knobloch, Edgar

    2016-11-01

    We study spatial localization in the real subcritical Ginzburg-Landau equation ut =m0 u +m1 cos2/π l x u +uxx +d | u | 2 u -| u | 4 u with spatially periodic forcing. When d > 0 and m1 = 0 this equation exhibits bistability between the trivial state u = 0 and a homogeneous nontrivial state u =u0 with stationary localized structures which accumulate at the Maxwell point m0 = - 3d2 / 16 . When spatial forcing is included its wavelength is imprinted on u0 creating conditions favorable to front pinning and hence spatial localization. We use numerical continuation to show that under appropriate conditions such forcing generates a sequence of localized states organized within a snakes-and-ladders structure centered on the Maxwell point, and refer to this phenomenon as forced snaking. We determine the stability properties of these states and show that longer lengthscale forcing leads to stationary trains consisting of a finite number of strongly localized, weakly interacting pulses exhibiting foliated snaking.

  17. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results; to aggregate these site- and technology-specific results to more general figures. The current report covers the results of the national implementation for Denmark. Three different fuel cycles have been chosen as case studies. These are fuel cycles for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant based on biogas. The report covers all the details of the application of the methodology to these fuel cycles aggregation to a national level. (au) EU-JOULE 3. 59 tabs., 25 ills., 61 refs.

  18. The Relationship between Internal Satisfaction and External Satisfaction amongst Hotel Customers in Malaysia

    OpenAIRE

    2012-01-01

    This paper is focused on hotel customers' internal and external satisfaction. Some previous studies had only focused on the customers' external satisfaction and only a few studies had managed to link between the two variables. The study also looked into factors which may act as internal variables such as the employer-employee relationship, employee relationship as well as employee- customer relationship. As for the external variables, these may involve looking into other aspects of satisfac...

  19. External fuel thermionic reactor system.

    Science.gov (United States)

    Mondt, J. F.; Peelgren, M. L.

    1971-01-01

    Thermionic reactors are prime candidates for nuclear electric propulsion. The national thermionic reactor effort is concentrated on the flashlight concept with the external-fuel concept as the backup. The external-fuel concept is very adaptable to a completely modular power subsystem which is attractive for highly reliable long-life applications. The 20- to 25-cm long, externally-fueled converters have been designed, fabricated, and successfully tested with many thermal cycles by electrical heating. However, difficulties have been encountered during encapsulation for nuclear heated tests and none have been started to date. These nuclear tests are required to demonstrate the concept feasibility.

  20. Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method

    OpenAIRE

    Andrews, O. D.; Bindoff, N. L.; P. R. Halloran; Ilyina, T.; Quéré, C.

    2013-01-01

    Ocean deoxygenation has been observed in all major ocean basins over the past 50 yr. Although this signal is largely consistent with oxygen changes expected from anthropogenic climate change, the contribution of external forcing to recent deoxygenation trends relative to natural internal variability is yet to be established. Here we conduct a formal optimal fingerprinting analysis to investigate if external forcing has had a detectable influence on observed dissolved oxygen ...

  1. Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method

    OpenAIRE

    Andrews, O. D.; Bindoff, N. L.; P. R. Halloran; Ilyina, T.; Le Quéré, C.

    2012-01-01

    Ocean deoxygenation has been observed in all major ocean basins over the past 50 yr. Although this signal is largely consistent with oxygen changes expected from anthropogenic climate change, the contribution of external forcing to recent deoxygenation trends relative to natural internal variability is yet to be established. Here we conduct a formal optimal fingerprinting analysis to investigate if external forcing has had a detectable influence on observed dissolved oxygen concentration ([O&...

  2. 金属推块V-带型CVT的研究--部分Ⅲ:金属推块上的作用力%A Study on a Metal pushing V-Belt Type CVT (Part 3: What Forces Act On Metal Blocks?)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    已经用试验实测了稳定工况下推块的压缩力和环的拉力。在以前的工作中已经概要地说明了这种带型的特殊的传动机理。 本文采用最近开发设计的推块测量在稳定工况下其他同时作用于推块上的力,这些力是推块和环之间的摩擦力,推块和带轮间的法向力,推块和带轮之间径向和切向摩擦力。根据新的试验数据来详细叙述金属推块V-带型CVT的传动机理。本文着重提出以下结论。 (1)在所有工况,推块和环结合的结合点在带轮上具有一个较大的节径,它与速比和传递转矩无关,在较小带轮上所有推块转速快于环,这决定着环的拉力。 (2)由于推块挤入从动带轮槽内,故产生推块压缩力的一次增加现象。 (3)因作用于推块侧面的法向力变大,故推块在大带轮的出口处径向摩擦力变成极大。%Block compression force and ring tension of a metal pushing V-belt type CVT have been experi[Abstract]Block compression force and ring tension of a metal pushing V-belt type CVT have been experimentally measured at steady states. The peculiar transmitting mechanisms for this type of belts has also been outlined based on the experimental results in the previous works. In this paper, other forces simultaneously acting on a block at steady states were measured using newly developed devised blocks. These forces are frictional force between blocks and rings, normal force between blocks and pulleys, frictional forces between blocks and pulleys in radial and tangential directions. The transmitting mechanisms for the metal pushing V-belt type CVT were drawn in detail based on new experimental data. The following conclusions are emphasized in the present work. (1) A cohesive point where the block coheres with the ring exists in the pulley having a larger pitch radius at all conditions. This is not dependent on speed ratio and trasmitting torque. The all blocks run faster than rings

  3. Intermolecular forces.

    Science.gov (United States)

    Buckingham, A D

    1975-11-06

    The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdividied into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed.

  4. Dynamical theory of active cellular response to external stress

    Science.gov (United States)

    de, Rumi; Safran, Samuel A.

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  5. Dynamical theory of active cellular response to external stress.

    Science.gov (United States)

    De, Rumi; Safran, Samuel A

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  6. Surface plasmon polariton assisted optical pulling force

    CERN Document Server

    Petrov, M I; Bogdanov, A A; Shalin, A S; Dogariu, A

    2016-01-01

    We demonstrate both analytically and numerically the existence of optical pulling forces acting on particles located near plasmonic interfaces. Two main factors contribute to the appearance of this negative reaction force. The interference between the incident and reflected waves induces a rotating dipole with an asymmetric scattering pattern while the directional excitation of surface plasmon polaritons (SPP) enhances the linear momentum of scattered light. The strongly asymmetric SPP excitation is determined by spin-orbit coupling of the rotating dipole and surface plasmon polariton. As a result of the total momentum conservation, the force acting on the particle points in a direction opposite to the incident wave propagation. We derive analytical expressions for the force acting on a dipolar particles placed in the proximity of plasmonic surfaces. Analytical expressions for this pulling force are derived within the dipole approximation and are in excellent agreement with results of electromagnetic numerica...

  7. Shear behavior of concrete beams externally prestressed with Parafil ropes

    Directory of Open Access Journals (Sweden)

    A.H. Ghallab

    2013-03-01

    Full Text Available Although extensive work has been carried out investigating the use of external prestressing system for flexural strengthening, a few studies regarding the shear behavior of externally prestressed beams can be found. Five beams, four of them were externally strengthened using Parafil rope, were loaded up to failure to investigate the effect of shear span/depth ratio, external prestressing force and concrete strength on their shear behavior. Test results showed that the shear span to depth ratio has a significant effect on both the shear strength and failure mode of the strengthened beams and the presence of external prestressing force increased the ultimate load of the tested beams by about 75%. Equations proposed by different codes for both the conventional reinforced concrete beams and for ordinary prestressed beams were used to evaluate the obtained experimental results. In general, codes equations showed a high level of conservatism in predicting the shear strength of the beams. Also, using the full strength rather than half of the concrete shear strength in the Egyptian code PC-method improves the accuracy of the calculated ultimate shear strength.

  8. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P. [eds.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results, to aggregate these site- and technology-specific results to more general figures. The current report covers the detailed information concerning the ExternE methodology. Importance is attached to the computer system used in the project and the assessment of air pollution effects on health, materials and ecological effects. Also the assessment of global warming damages are described. Finally the report covers the detailed information concerning the national implementation for Denmark for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant base on biogas. (au) EU-JOULE 3. 79 tabs., 11 ills., 201 refs.

  9. Collaborating with EPA through the Federal Technology Transfer Act

    Science.gov (United States)

    Under the Federal Technology Transfer Act (FTTA), EPA can collaborate with external parties on research projects, and share research materials. Learn more about the types of partnerships the EPA offers.

  10. Externality and burnout among dentists.

    Science.gov (United States)

    St-Yves, A; Freeston, M H; Godbout, F; Poulin, L; St-Amand, C; Verret, M

    1989-12-01

    This study investigates the relationship between burnout as measured by the Maslach Burnout Inventory and locus of control as measured by the Adult Nowicki-Strickland Internal-External Locus of Control (ANS-IE) for 82 dentists. Significant Pearson correlations between two Maslach subscales and locus of control show Personal Accomplishment to be negatively associated -.31 and Emotional Exhaustion to be positively correlated .21 to externality.

  11. Relatie interne en externe audit

    OpenAIRE

    Ghys, Emelie

    2011-01-01

    In het eerste hoofdstuk wordt de probleemstelling van deze eindverhandeling besproken. Interne en externe audit worden de laatste jaren internationaal en nationaal meer en meer erkend in het bedrijfsleven. Aanleiding voor de toenemende belangstelling van de interne en externe auditfunctie zijn de verschillende boekhoudschandalen rond corporate governance of deugdelijk bestuur. Deze financiële mislukkingen leidden wereldwijd tot diverse wetten, nieuwe regels en verbeterde standaarden om zo een...

  12. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    as a market mechanism that can be brought inside the firm to provide incentives for continuous improvement and the development of competitive advances. However, whereas extant research primarily has focused on the importance and effects of using external benchmarks, less attention has been directed towards...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  13. Parallel External Memory Graph Algorithms

    DEFF Research Database (Denmark)

    Arge, Lars Allan; Goodrich, Michael T.; Sitchinava, Nodari

    2010-01-01

    In this paper, we study parallel I/O efficient graph algorithms in the Parallel External Memory (PEM) model, one o f the private-cache chip multiprocessor (CMP) models. We study the fundamental problem of list ranking which leads to efficient solutions to problems on trees, such as computing lowest...... an optimal speedup of ¿(P) in parallel I/O complexity and parallel computation time, compared to the single-processor external memory counterparts....

  14. Possible External Forcing Factors for the Interdecadal Change in the East Asian Winter Monsoon around the Late 1990s%20世纪90年代末东亚冬季风年代际变化的外强迫因子分析

    Institute of Scientific and Technical Information of China (English)

    肖晓; 陈文; 范广洲; 周定文

    2016-01-01

    In this study, the authors investigate the effects of anomalous sea surface temperature (SST), sea ice, and snow cover in the interdecadal change in the East Asian Winter Monsoon (EAWM) that occurred around the late 1990s by using reanalysis datasets from NCEP/NCAR, the Met Office Hadley Centre, the NOAA Climate Diagnostic Center, and the Northern Hemisphere snow cover reanalysis product from NOAA. Characteristics of and mechanisms for the interdecadal changes in the EAWM that occurred around mid-1980s (1976−1988) and late 1990s (1999−2012) are also compared. Results indicate that the interdecadal change in the EAWM that occurred around mid-1980s is characterized by negative temperature anomalies over the entire areas of China. The interdecadal change in the EAWM that occurred around mid-1980s is not related to external forcing including SST and sea ice anomalies. Instead, it is attributed to internal atmospheric dynamics. However, the interdecadal change in the EAWM that occurred around the late 1990s may be attributed to external forcing of SST, sea ice and snow cover anomalies in the preceding fall and winter. Particularly, the warmer SST in the late 1990s over the North Atlantic triggered an atmospheric wave train that propagated eastward and reached East Asia. This wave train intensified Siberian high, leading to a stronger EAWM and negative temperature anomalies over northern East Asia. The reduced sea ice anomalies in the Arctic Ocean and the increased snow cover over the Eurasian Continent in the preceding autumn is also a possible reason for the interdecadal change in the EAWM occurred around the late 1990s. In addition, positive SST anomalies over the tropical western Pacific can lead to convergence and enhanced convection over the maritime continent. As a result, cyclonic circulation anomalies over the tropical eastern Indian Ocean developed via a Gill type response. The anomalous southerly winds to the east of the cyclone eventually led to positive

  15. Force-Mediated Kinetics of Single P-Selectin/Ligand Complexes Observed by Atomic Force Microscopy

    Science.gov (United States)

    Fritz, Jurgen; Katopodis, Andreas G.; Kolbinger, Frank; Anselmetti, Dario

    1998-10-01

    Leukocytes roll along the endothelium of postcapillary venules in response to inflammatory signals. Rolling under the hydrodynamic drag forces of blood flow is mediated by the interaction between selectins and their ligands across the leukocyte and endothelial cell surfaces. Here we present force-spectroscopy experiments on single complexes of P-selectin and P-selectin glycoprotein ligand-1 by atomic force microscopy to determine the intrinsic molecular properties of this dynamic adhesion process. By modeling intermolecular and intramolecular forces as well as the adhesion probability in atomic force microscopy experiments we gain information on rupture forces, elasticity, and kinetics of the P-selectin/P-selectin glycoprotein ligand-1 interaction. The complexes are able to withstand forces up to 165 pN and show a chain-like elasticity with a molecular spring constant of 5.3 pN nm-1 and a persistence length of 0.35 nm. The dissociation constant (off-rate) varies over three orders of magnitude from 0.02 s-1 under zero force up to 15 s-1 under external applied forces. Rupture force and lifetime of the complexes are not constant, but directly depend on the applied force per unit time, which is a product of the intrinsic molecular elasticity and the external pulling velocity. The high strength of binding combined with force-dependent rate constants and high molecular elasticity are tailored to support physiological leukocyte rolling.

  16. Matter-screened Casimir force and Casimir-Polder force in planar structures

    CERN Document Server

    Raabe, C; Raabe, Christian; Welsch, Dirk-Gunnar

    2005-01-01

    Using a recently developed theory of the Casimir force (Raabe C and Welsch D-G 2005 Phys. Rev. A 71 013814), we calculate the force that acts on a plate in front of a planar wall and the force that acts on the plate in the case where the plate is part of matter that fills the space in front of the wall. We show that in the limit of a dielectric plate whose permittivity is close to unity, the force obtained in the former case reduces to the ordinary, i.e., unscreened Casimir-Polder force acting on isolated atoms. In the latter case, the theory yields the Casimir-Polder force that is screened by the surrounding matter.

  17. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  18. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective of...

  19. Axial force measurement for esophageal function testing

    DEFF Research Database (Denmark)

    Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans

    2009-01-01

    force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...

  20. DNA under Force: Mechanics, Electrostatics, and Hydration

    Directory of Open Access Journals (Sweden)

    Jingqiang Li

    2015-02-01

    Full Text Available Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology.

  1. Identifying external influences on global precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, K.; Bonfils, C.

    2013-11-11

    Changes in global (ocean and land) precipitation are among the most important and least well-understood consequences of climate change. Increasing greenhouse gas concentrations are thought to affect the zonal-mean distribution of precipitation through two basic mechanisms. First, increasing temperatures will lead to an intensification of the hydrological cycle (“thermodynamic” changes). Second, changes in atmospheric circulation patterns will lead to poleward displacement of the storm tracks and subtropical dry zones and to a widening of the tropical belt (“dynamic” changes). We demonstrate that both these changes are occurring simultaneously in global precipitation, that this behavior cannot be explained by internal variability alone, and that external influences are responsible for the observed precipitation changes. Whereas existing model experiments are not of sufficient length to differentiate between natural and anthropogenic forcing terms at the 95% confidence level, we present evidence that the observed trends result from human activities.

  2. A brief history of the Coriolis force

    NARCIS (Netherlands)

    Gerkema, T.; Gostiaux, L.

    2012-01-01

    In 1835, Gustave Coriolis derived the expression of a force acting in rotating systems, now known as the Coriolis force. His work was inspired by rotating devices such as waterwheels. However, the onerotating device that has always been with us is the Earth itself. Indeed, the earliest studies on ho

  3. Radiation Forces and Torques without Stress (Tensors)

    Science.gov (United States)

    Bohren, Craig F.

    2011-01-01

    To understand radiation forces and torques or to calculate them does not require invoking photon or electromagnetic field momentum transfer or stress tensors. According to continuum electromagnetic theory, forces and torques exerted by radiation are a consequence of electric and magnetic fields acting on charges and currents that the fields induce…

  4. Mathematical Model of Gravitational and Electrostatic Forces

    OpenAIRE

    Krouglov, Alexei

    2006-01-01

    Author presents mathematical model for acting-on-a-distance attractive and repulsive forces based on propagation of energy waves that produces Newton expression for gravitational and Coulomb expression for electrostatic forces. Model uses mathematical observation that difference between two inverse exponential functions of the distance asymptotically converges to function proportional to reciprocal of distance squared.

  5. Radiation Forces and Torques without Stress (Tensors)

    Science.gov (United States)

    Bohren, Craig F.

    2011-01-01

    To understand radiation forces and torques or to calculate them does not require invoking photon or electromagnetic field momentum transfer or stress tensors. According to continuum electromagnetic theory, forces and torques exerted by radiation are a consequence of electric and magnetic fields acting on charges and currents that the fields induce…

  6. Containment atmosphere response to external sprays

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.; Almenas, K. [Univ. of Maryland, College Park, MD (United States)

    1995-09-01

    The application of external sprays to a containment steel shell can be an effective energy removal method and has been proposed in the passive AP-600 design. Reduction of the steel shell temperature in contact with the containment atmosphere enhances both heat and mass transfer driving forces. Large scale experimental data in this area is scarce, therefore the measurements obtained from the E series tests conducted at the German HDR facility deserve special attention. These long term tests simulated various severe accident conditions, including external spraying of the hemispherical steel shell. This investigation focuses upon the integral response of the HDR containment atmosphere during spray periods and upon methods by which lumped parameter system codes, like CONTAIN, model the underlying condensation phenomena. Increases in spray water flowrates above a minimum value were ineffective at improving containment pressure reduction since the limiting resistance for energy transfer lies in the noncondensable-vapor boundary layer at the inner condensing surface. The spray created an unstable condition by cooling the upper layers of a heated atmosphere and thus inducing global natural circulation flows in the facility and subsequently, abrupt changes in lighter-than-air noncondensable (J{sub 2}/He) concentrations. Modeling results using the CONTAIN code are outlined and code limitations are delineated.

  7. 75 FR 52597 - Availability of Interim Procedures for Federal External Review and Model Notices Relating to...

    Science.gov (United States)

    2010-08-26

    ... processes under the Patient Protection and Affordable Care Act. FOR FURTHER INFORMATION CONTACT: Amy Turner... Federal external review process. (In the case of health insurance coverage offered in connection with a... excise tax liability should be reported on IRS Form 8928 with respect to PHS Act section...

  8. External Validation of the COmorbidity Test.

    Science.gov (United States)

    Villalobos, Nicholas; Davidson, Ross; Ghori, Uzair K; Abdou, Yara; Abukhalaf, Jawad; Guillamet, Rodrigo Vazquez

    2017-10-01

    The COmorbidity TEst (COTE) is a Chronic Obstructive Pulmonary Disease (COPD)-specific co-morbidity score created to predict mortality. Before its wide application at the University of New Mexico we intended to validate it. The study was conducted at the University of New Mexico Hospital (UNMH) in Albuquerque, NM, USA, a tertiary academic hospital. Consecutive patients with the clinical diagnosis of COPD were identified using the hospital's medical records system and included if they were older than 40 years, had smoked at least 20 pack-years and their post bronchodilator forced expiratory volume in the first second/forced vital capacity (FEV1/FVC) was <0.7 without an alternative diagnosis. The data collected included demographics, co-morbidities as described in the COTE, COPD-specific therapies, spirometry results and mortality. Of 317 patients 51.4% were male, average age was 65.6 ± 9.6 years and the mean post-bronchodilator FEV1 percent predicted (FEV1%) was 52.9 ± 16.9%. 31 (9.8%) patients were on triple long-acting bronchodilator inhaler therapy, 88 (27.8%) on two long-acting bronchodilators and 163 (51.4%) on at least one long-acting bronchodilator. The median follow-up was 3.5 years (IQR = 1.9-6.9). Fifty four patients died by the end of the follow-up period and their median COTE of 4 (IQR = 1-8) was significantly higher than for the survivors with COTE = 1 (IQR = 0-6; p = 0.002). In univariable analyses COTE was positively associated while FEV1%, body mass index (BMI) and gender were negatively associated with all-cause mortality. In multivariable analysis BMI, FEV1% and COTE remained independent predictors for mortality. The COTE is an independent predictor of mortality for COPD patients at UNMH.

  9. Force decomposition in robot force control

    Science.gov (United States)

    Murphy, Steve H.; Wen, John T.

    1991-01-01

    The unit inconsistency in force decomposition has motivated an investigation into the force control problem in multiple-arm manipulation. Based on physical considerations, it is argued that the force that should be controlled is the internal force at the specified frame in the payload. This force contains contributions due to both applied forces from the arms and the inertial force from the payload and the arms. A least-squares scheme free of unit inconsistency for finding this internal force is presented. The force control issue is analyzed, and an integral force feedback controller is proposed.

  10. From Territorial Defence to Expeditionary Forces

    DEFF Research Database (Denmark)

    Nyemann, Dorthe; Staun, Jørgen Meedom

    2016-01-01

    After the Cold War the Danish Armed Forces moved away from its traditional role of territorial defense of Danish soil and towards a role as a globally deployable expeditionary force, imbedded with UK and/or US forces. This shift in national strategy amplified the requirements of the young officer......’ ability to think and act strategically in international missions. This article discusses to what extent this has been reflected in the education of the young officers....

  11. Measurement of edgewise torque force in vitro.

    Science.gov (United States)

    Steyn, C L

    1977-05-01

    The construction of a model for the measurement of palatal root torque is described. It was demonstrated that: 1. Halfway between the apex of a tooth and the arch wire the force was double that which was delivered at the apex. 2. The lateral incisors were subjected to appreciably more force than the central incisors. 3. The smaller the number of teeth acted upon, the greater the force they received.

  12. Force focusing in confined fibres and sheets

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Victor; Cerda, Enrique [Departamento de Fisica, Universidad de Santiago, Av. Ecuador 3493, Santiago (Chile); Witten, T A; Liang Tao [James Franck Institute, University of Chicago, Chicago IL 60637 (United States)], E-mail: t-witten@uchicago.edu

    2008-07-07

    A thin fibre or sheet curled into a circular container has a detached region whose shape and force ratios are independent of material properties and container radius. We compute this shape and compare it with experiments. The discrete forces acting at either end of the detached region have a ratio that depends only on the length of the fibre or sheet relative to the circle radius. We calculate this force ratio in three regimes of circle radius. (fast track communication)

  13. Electric charges and forces in atomic force microscopy and nano-xerography

    Energy Technology Data Exchange (ETDEWEB)

    Stemmer, A; Ziegler, D; Seemann, L; Naujoks, N [Nanotechnology Group, ETH Zurich, Tannenstrasse 3, 8092 Zurich (Switzerland); Rychen, J [Nanonis GmbH, Technoparkstrasse 1, 8005 Zurich (Switzerland)], E-mail: astemmer@ethz.ch

    2008-12-01

    Electrostatic forces generated by contact potential differences, localized charges, or externally applied voltages play a crucial role in atomic force microscopy. Electrostatic forces mediate the non-contact measurement of local potentials by the Kelvin probe technique, enabling compositional mapping of surfaces. However, if not compensated properly, electrostatic forces lead to height errors in topography images acquired in tapping mode. We present a single scan Kelvin probe force microscopy technique that compensates local electrostatic forces and allows simultaneous height and potential measurements in tapping mode. Electrostatic forces also direct the localized assembly of structures in nano-xerography. Here we describe how positive charges, written into a thin film of poly(methyl)methacrylate with the conductive tip of an atomic force microscope, guide the deposition of carboxyl-functionalized multiwalled carbon nanotubes suspended in isopropyl-alcohol.

  14. Maximal loads acting on legs of powered roof support unit in longwalls with bumping hazards

    Institute of Scientific and Technical Information of China (English)

    Stanislaw Szweda

    2001-01-01

    acting on a unit du ring blasting. The majority of recorded force changes in the legs has been caused by a dyna mic interaction of the roof. They are characterized by a load increase coefficie nt Kd, satisfying the inequality 1.06external load acted on the bases, w as recorded. Individual, recorded results of measurements indicate that changes of the force in the legs, caused by external loads of this type, run more inten sively due to roof loads (1.08forces in the legs, caused by a dynamic interacti on of the floor and the bases and the mining and geological conditions requires a performance of additional underground tests.

  15. Thermodynamic cost of external control

    Science.gov (United States)

    Barato, Andre C.; Seifert, Udo

    2017-07-01

    Artificial molecular machines are often driven by the periodic variation of an external parameter. This external control exerts work on the system of which a part can be extracted as output if the system runs against an applied load. Usually, the thermodynamic cost of the process that generates the external control is ignored. Here, we derive a refined second law for such small machines that include this cost, which is, for example, generated by free energy consumption of a chemical reaction that modifies the energy landscape for such a machine. In the limit of irreversible control, this refined second law becomes the standard one. Beyond this ideal limiting case, our analysis shows that due to a new entropic term unexpected regimes can occur: the control work can be smaller than the extracted work and the work required to generate the control can be smaller than this control work. Our general inequalities are illustrated by a paradigmatic three-state system.

  16. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    This paper reviews research on open innovation that considers how and why firms commercialize external sources of innovations. It examines both the “outside-in” and “coupled” modes of open innovation. From an analysis of prior research on how firms leverage external sources of innovation...... cited work beyond those journals. A review of 291 open innovation-related publications from these sources shows that the majority of these articles indeed address elements of this inbound open innovation process model. Specifically, it finds that researchers have front-loaded their examination...... external innovations create value rather than how firms capture value from those innovations. Finally, the interaction phase considers both feedback for the linear process and reciprocal innovation processes such as cocreation, network collaboration, and community innovation. This review and synthesis...

  17. Quasistatic Modeling of Concentric Tube Robots with External Loads.

    Science.gov (United States)

    Lock, Jesse; Laing, Genevieve; Mahvash, Mohsen; Dupont, Pierre E

    2010-12-03

    Concentric tube robots are a subset of continuum robots constructed by combining pre-curved elastic tubes. As the tubes are rotated and translated with respect to each other, their curvatures interact elastically, enabling control of the robot's tip configuration as well as the curvature along its length. This technology is projected to be useful in many types of minimally invasive medical procedures. Because these robots are flexible by design, they deflect considerably when applying forces to the external environment. Thus, in contrast to rigid-link robots, their kinematic and static force models are coupled. This paper derives a multi-tube quasistatic model that relates tube rotations and translations together with externally applied loads to robot shape and tip configuration. The model can be applied in robot design, procedure planning as well as control. For validation, the multi-tube model is compared experimentally to a computationally-efficient single-tube approximate model.

  18. Thermodynamic Branch in the Chemical System Response to External Impact

    CERN Document Server

    Zilbergleyt, B

    2012-01-01

    The paper gives an account of a detailed investigation of the thermodynamic branch as a path of the chemical system deviation from its isolated thermodynamic equilibrium under an external impact. For a combination of direct and reverse reactions in the same chemical system, full thermodynamic branch is presented by an S-shaped curve, whose ends asymptotically achieve appropriate initial states, which, in turn, are logistic ends of the opposite reactions. The slope tangents of the steepest parts of the curves, the areas of the maximum rate of the shift growth vs. the external thermodynamic force, occurred to be directly proportional to the force and, simultaneously, linearly proportional to the thermodynamic equivalent of chemical reaction, which is the ratio between the amount in moles of any reaction participant, transformed in an isolated system, along the reaction way from its initial state to thermodynamic equilibrium, to its stoichiometric coefficient. The found linearity is valid for arbitrary combinati...

  19. Effect of various periodic forces on Duffing oscillator

    Indian Academy of Sciences (India)

    V Ravichandran; V Chinnathambi; S Rajasekar

    2006-08-01

    Bifurcations and chaos in the ubiquitous Duffing oscillator equation with different external periodic forces are studied numerically. The external periodic forces considered are sine wave, square wave, rectified sine wave, symmetric saw-tooth wave, asymmetric saw-tooth wave, rectangular wave with amplitude-dependent width and modulus of sine wave. Period doubling bifurcations, chaos, intermittency, periodic windows and reverse period doubling bifurcations are found to occur due to the applied forces. A comparative study of the effect of various forces is performed.

  20. The Role of Magnetic Forces in Biology and Medicine

    OpenAIRE

    Roth, Bradley J.

    2011-01-01

    The Lorentz force (the force acting on currents in a magnetic field) plays an increasingly larger role in techniques to image current and conductivity. This review will summarize several applications involving the Lorentz force, including 1) magneto-acoustic imaging of current, 2) “Hall effect” imaging, 3) ultrasonically-induced Lorentz force imaging of conductivity, 4) magneto-acoustic tomography with magnetic induction, and 5) Lorentz force imaging of action currents using magnetic resonanc...

  1. Delayed-feedback chimera states: Forced multiclusters and stochastic resonance

    Science.gov (United States)

    Semenov, V.; Zakharova, A.; Maistrenko, Y.; Schöll, E.

    2016-07-01

    A nonlinear oscillator model with negative time-delayed feedback is studied numerically under external deterministic and stochastic forcing. It is found that in the unforced system complex partial synchronization patterns like chimera states as well as salt-and-pepper-like solitary states arise on the route from regular dynamics to spatio-temporal chaos. The control of the dynamics by external periodic forcing is demonstrated by numerical simulations. It is shown that one-cluster and multi-cluster chimeras can be achieved by adjusting the external forcing frequency to appropriate resonance conditions. If a stochastic component is superimposed to the deterministic external forcing, chimera states can be induced in a way similar to stochastic resonance, they appear, therefore, in regimes where they do not exist without noise.

  2. Internal and external North Atlantic Sector variability in the Kiel climate model

    Energy Technology Data Exchange (ETDEWEB)

    Latif, Mojib; Park, Wonsun; Ding, Hui; Keenlyside, Noel S. [Leibniz-Inst. fuer Meereswissenschaften, Kiel (Germany)

    2009-08-15

    The internal and external North Atlantic Sector variability is investigated by means of a multimillennial control run and forced experiments with the Kiel Climate Model (KCM). The internal variability is studied by analyzing the control run. The externally forced variability is investigated in a run with periodic millennial solar forcing and in greenhouse warming experiments with enhanced carbon dioxide concentrations. The surface air temperature (SAT) averaged over the Northern Hemisphere simulated in the control run displays enhanced variability relative to the red background at decadal, centennial, and millennial timescales. Special emphasis is given to the variability of the Meridional Overturning Circulation (MOC). The MOC plays an important role in the generation of internal climate modes. Furthermore, the MOC provides a strong negative feedback on the Northern Hemisphere SAT in both the solar and greenhouse warming experiments, thereby moderating the direct effects of the external forcing in the North Atlantic. The implications of the results for decadal predictability are discussed. (orig.)

  3. Optimal Auctions with Financial Externalities

    NARCIS (Netherlands)

    Maasland, E.; Onderstal, A.M.

    2002-01-01

    We construct optimal auctions when bidders face financial externalities.In a Coasean World, in which the seller cannot prevent a perfect resale market, nor withhold the object, the lowest-price all-pay auction is optimal.In a Myersonean World, in which the seller can both prevent resale after the au

  4. Organizing for External Knowledge Sourcing

    DEFF Research Database (Denmark)

    Rabbiosi, Larissa; Reichstein, Toke

    2011-01-01

    The aim of this article is to provide an introduction to the special issue. We briefly consider the external knowledge sourcing and organizing for innovation literatures, which offer a background for the special issue, and we highlight their mutual dialogue. We then illustrate the main findings...

  5. Measuring Externalities in Program Evaluation

    NARCIS (Netherlands)

    Janssens, Wendy

    2005-01-01

    Impact evaluations of development programmes usually focus on a comparison of participants with a control group. However, if the programme generates externalities for non-participants such an approach will capture only part of the programme's impact. Based on a unique large-scale quantitative survey

  6. Lupus vulgaris of external nose.

    Science.gov (United States)

    Bhandary, Satheesh Kumar; Ranganna, B Usha

    2008-12-01

    Lupus vulgaris is the commonest form of cutaneous tuberculosis which commonly involve trunk and buttocks. Lupus vulgaris affecting nose and face, are rarely reported in India. This study reports an unusual case of lupus vulgaris involving the external nose that showed dramatic outcome after six months of anti- tubercular treatment.

  7. [Treatment by external insulin pump].

    Science.gov (United States)

    Clavel, Sylvaine

    2010-12-01

    Since the recent recommendations by the French speaking association for research on diabetes and metabolic illnesses (Alfediam), treatment by insulin pump has found itself in competition with basal-bolus, a procedure using similar injections of insulin which has become a benchmark treatment. The latest Alfediam guidelines focus on defining ways of treating diabetics with an external insulin pump.

  8. Matchings with Externalities and Attitudes

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal;

    2013-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real-life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas ...

  9. Post-external dacryocystorhinostomy lagophthalmos.

    Science.gov (United States)

    Odat, Thabit A; Odat, Haitham A; Khraisat, Heba; Odat, Mohannad A; Alzoubi, Firas Q

    2015-06-01

    To describe lagophthalmos and eyelid closure abnormality after external dacryocystorhinostomy (DCR). A retrospective review of medical records and postoperative photographs of 79 patients who underwent external DCR for nasolacrimal duct obstruction and developed eyelid closure abnormality and lagophthalmos with or without exposure keratopathy was conducted. Collected data included age, sex, indication for surgery, laterality, length and type of incision, length of follow-up duration, presence of punctate epithelial keratopathy, and time for resolution of eyelid closure abnormalities. Twenty-seven patients with 28 external dacryocystorhinostomy had postoperative eyelid closure abnormalities. Male to female ratio was 1:6. The mean age was 40.1 years (range 9-80 years). All surgeries were performed through diagonal skin incision. Lagophthalmos involving the medial third of the palpebral fissure was noticed in 28.6 % of cases. All patients had hypometric blink mainly of the upper eyelid. One patient had punctate epithelial keratopathy. Resolution of lagophthalmos was noticed over a period of 1-5 weeks with an average of 3 weeks. None of the patients continued to have residual hypometric blink or punctate keratopathy at the last follow-up time. The mean follow-up period was 4.2 months (range 3-6 months). Eyelid closure abnormality and lagophthalmos after external DCR are underestimated problems. Spontaneous resolution is seen in all cases weeks to months after surgery.

  10. Femoral Reconstruction Using External Fixation

    Directory of Open Access Journals (Sweden)

    Yevgeniy Palatnik

    2011-01-01

    Full Text Available Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD, limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD and lateral distal femoral angle (LDFA for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction.

  11. Measurement of Prestressing Force in Pretensioned UHPC Deck Using a Fiber Optic FBG Sensor Embedded in a 7-Wire Strand

    Directory of Open Access Journals (Sweden)

    Jae-min Kim

    2016-01-01

    Full Text Available This paper presents the results of the performance test and long-term monitoring of the prestressing force inside concrete performed on a pretensioned Ultra-High Performance Concrete (UHPC deck. The force is measured by applying a 7-wire strand embedded with an FBG (Fiber Bragg Grating sensor. The performance test was conducted on a 3.7 m × 1.8 m pretensioned deck specimen through wheel loading tests to verify the applicability of the measurement method. In addition, a 12.3 m long and 4.8 m wide bridge with a pretensioned UHPC deck was erected and long-term monitoring was conducted over three years to verify the applicability of the method to real bridges. The effectiveness of the measurement method of the prestressing force inside concrete is verified, and the long-term monitoring data are used to investigate various temperature compensation methods. The results show that the proposed method enables effective measurement of small changes in the prestressing force inside the concrete. These changes are caused by the external forces acting on the bridge in service and provide sufficient durability for long-term sensing. The analysis of the prestressing force obtained through long-term monitoring reveals the necessity of conducting temperature compensation for the consistency of the data acquired using the FBG sensor. Moreover, the selection of the thermal expansion coefficient appears also to be of critical importance for temperature compensation.

  12. Archimedes Force on Casimir Apparatus

    CERN Document Server

    Shevchenko, Vladimir

    2016-01-01

    We address a problem of Casimir apparatus in dense medium and weak gravitational field. The falling of the apparatus has to be governed by the equivalence principle, with proper account for contributions to the weight of the apparatus from its material part and from distorted quantum fields. We discuss general expression for the corresponding force in metric with cylindrical symmetry. By way of example we compute explicit expression for Archimedes force, acting on the Casimir apparatus of finite size, immersed into thermal bath of free scalar field. It is shown that besides universal term, proportional to the volume of the apparatus, there are non-universal quantum corrections, depending on the boundary conditions.

  13. Ultrasonic Force Microscopies

    Science.gov (United States)

    Kolosov, Oleg; Briggs, Andrew

    Ultrasonic Force Microscopy, or UFM, allows combination of two apparently mutually exclusive requirements for the nanomechanical probe—high stiffness for the efficient indentation and high mechanical compliance that brings force sensitivity. Somewhat inventively, UFM allows to combine these two virtues in the same cantilever by using indention of the sample at high frequency, when cantilever is very rigid, but detecting the result of this indention at much lower frequency. That is made possible due to the extreme nonlinearity of the nanoscale tip-surface junction force-distance dependence, that acts as "mechanical diode" detecting ultrasound in AFM. After introducing UFM principles, we discuss features of experimental UFM implementation, and the theory of contrast in this mode, progressing to quantitative measurements of contact stiffness. A variety of UFM applications ranging from semiconductor quantum nanostructures, graphene, very large scale integrated circuits, and reinforced ceramics to polymer composites and biological materials is presented via comprehensive imaging gallery accompanied by the guidance for the optimal UFM measurements of these materials. We also address effects of adhesion and topography on the elasticity imaging and the approaches for reducing artifacts connected with these effects. This is complemented by another extremely useful feature of UFM—ultrasound induced superlubricity that allows damage free imaging of materials ranging from stiff solid state devices and graphene to biological materials. Finally, we proceed to the exploration of time-resolved nanoscale phenomena using nonlinear mixing of multiple vibration frequencies in ultrasonic AFM—Heterodyne Force Microscopy, or HFM, that also include mixing of ultrasonic vibration with other periodic physical excitations, eg. electrical, photothermal, etc. Significant section of the chapter analyzes the ability of UFM and HFM to detect subsurface mechanical inhomogeneities, as well as

  14. Independence of biomechanical forces and craniofacial pneumatization in Cebus.

    Science.gov (United States)

    Rae, Todd C; Koppe, Thomas

    2008-11-01

    Several different factors have been hypothesized as explanations of variation in primate paranasal sinus size. Biomechanical forces, particularly those associated with mastication, are frequently evoked to account for differences in primate craniofacial pneumatization. To test whether masticatory stresses are responsible for maxillary sinus volume diversity, two platyrrhine species of the genus Cebus (C. apella and C. albifrons) were examined. The former has been identified as a hard object feeder, and many morphological differences between the two species are attributable to differences in the mechanical properties of their respective diets. Sinus volumes were derived from serial coronal CT scans of the crania of adults. Several external cranial measurements were used to scale sinus volume relative to the size of the face. Relative measures of maxillary sinus volume were compared using standard statistical techniques. In all comparisons, the two capuchin species do not differ from one another significantly at P < 0.05. Thus, this "natural experiment" fails to support the interpretation that biomechanical forces acting on the facial skeleton substantially affect the degree of paranasal pneumatization in primates. This result suggests that it is unlikely that the maxillary sinus performs any function in relation to masticatory stress; other factors must be responsible for the variation in sinus volume among primates. Copyright 2008 Wiley-Liss, Inc.

  15. Size Dependent Orientation of Knudsen Force

    KAUST Repository

    Zhu, Taishan

    2012-03-03

    Knudsen force acting on a heated microbeam adjacent to a cold substrate in a rarefied gas is a mechanical force created by unbalanced thermal gradients. The measured force has its direction pointing towards the side with a lower thermal gradient and its magnitude vanishes in both continuum and free-molecule limits. In our previous study, negative Knudsen forces were discovered at the high Knudsen regime before diminishing in the free-molecule limit. Such a phenomenon was however not observed in the experiment. In this paper, the existence of such a negative Knudsen force is further confirmed using both numerical simulation and theoretical analysis. The asymptotic order of the Knudsen force near the collisionless limit is analyzed and the analytical expression of its leading term is provided, from which approaches for the enhancement of negative Knudsen forces are proposed. Copyright © 2012 by ASME.

  16. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    .g. sustainability or quality of life. The purpose of this paper is to explore how and to what extent public sector interventions that aim at forcing cluster development in industries can support sustainable development as defined in the Brundtland tradition and more recently elaborated in such concepts as eco......, Portugal and New Zealand have adopted the concept. Public sector interventions that aim to support cluster development in industries most often focus upon economic policy goals such as enhanced employment and improved productivity, but rarely emphasise broader societal policy goals relating to e...... to the automotive sector in Wales. Specifically, the paper evaluates the "Accelerates" programme initiated by the Welsh Development Agency and elaborates on how and to what extent the Accelerate programme supports the development of a sustainable automotive industry cluster. The Accelerate programme was set up...

  17. Coriolis Force

    Science.gov (United States)

    Marciuc, Daly; Solschi, Viorel

    2017-04-01

    Understanding the Coriolis effect is essential for explaining the movement of air masses and ocean currents. The lesson we propose aims to familiarize students with the manifestation of the Coriolis effect. Students are guided to build, using the GeoGebra software, a simulation of the motion of a body, related to a rotating reference system. The mathematical expression of the Coriolis force is deduced, for particular cases, and the Foucault's pendulum is presented and explained. Students have the opportunity to deepen the subject, by developing materials related to topics such as: • Global Wind Pattern • Ocean Currents • Coriolis Effect in Long Range Shooting • Finding the latitude with a Foucault Pendulum

  18. Dipolar fluids under external perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, Sabine H L [Stranski-Laboratorium fuer Physikalische und Theoretische Chemie Sekretariat TC7, Technische Universitaet Berlin, Strasse des 17. Juni 124, D-10623 Berlin (Germany)

    2005-04-20

    We discuss recent developments and present new findings on the structural and phase properties of dipolar model fluids influenced by various external perturbations. We concentrate on systems of spherical particles with permanent (point) dipole moments. Starting from what is known about the three-dimensional systems, particular emphasis is given to dipolar fluids in different confining situations involving both simple and complex (disordered) pore geometries. Further topics concern the effect of quenched positional disorder, the influence of external (electric or magnetic) fields, and the fluid-fluid phase behaviour of various dipolar mixtures. It is demonstrated that due to the translational-orientational coupling and due to the long range of dipolar interactions even simple perturbations such as hard walls can have a profound impact on the systems. (topical review)

  19. External observer reflections on QBism

    CERN Document Server

    Khrennikov, Andrei

    2015-01-01

    In this short review I present my personal reflections on QBism. I have no intrinsic sympathy neither to QBism nor to subjective interpretation of probability in general. However, I have been following development of QBism from its very beginning, observing its evolution and success, sometimes with big surprise. Therefore my reflections on QBism can be treated as "external observer" reflections. I hope that my representation of this interpretation of quantum mechanics (QM) has some degree of objectivity. It may be useful for researchers who are interested in quantum foundations, but do not belong to the QBism-community, because I tried to analyze essentials of QBism critically (i.e., not just emphasizing its advantages, as in a typical publication of QBists). QBists may be interested as well - in comments of an external observer who monitored development of this approach to QM during last 16 years. The second part of the paper is devoted to interpretations of probability, objective versus subjective, and view...

  20. Firm Search for External Knowledge

    DEFF Research Database (Denmark)

    Sofka, Wolfgang; Grimpe, Christoph

    2012-01-01

    The innovation performance of modern firms is increasingly determined by their ability to search and absorb external knowledge. However, after a certain threshold firms "oversearch" their environment and innovation performance declines. In this paper, we argue that prior literature has largely...... ignored the institutional context that provides or denies access to external knowledge at the country level. Combining institutional and knowledge search theory, we suggest that the market orientation of the institutional environment and the magnitude of institutional change influence when firms begin...... to experience the negative performance effects of oversearch. Based on a comprehensive sample of almost 8,000 firms from ten European countries, we find that institutions matter considerably for firms' search activity. Higher market orientation of institutions increases the effectiveness of firms' search...

  1. MGR External Events Hazards Analysis

    Energy Technology Data Exchange (ETDEWEB)

    L. Booth

    1999-11-06

    The purpose and objective of this analysis is to apply an external events Hazards Analysis (HA) to the License Application Design Selection Enhanced Design Alternative 11 [(LADS EDA II design (Reference 8.32))]. The output of the HA is called a Hazards List (HL). This analysis supersedes the external hazards portion of Rev. 00 of the PHA (Reference 8.1). The PHA for internal events will also be updated to the LADS EDA II design but under a separate analysis. Like the PHA methodology, the HA methodology provides a systematic method to identify potential hazards during the 100-year Monitored Geologic Repository (MGR) operating period updated to reflect the EDA II design. The resulting events on the HL are candidates that may have potential radiological consequences as determined during Design Basis Events (DBEs) analyses. Therefore, the HL that results from this analysis will undergo further screening and analysis based on the criteria that apply during the performance of DBE analyses.

  2. Wall force produced during disruptions

    Science.gov (United States)

    Strauss, H.; Paccagnella, R.; Breslau, J.

    2009-11-01

    The study of disruptions is of great importance for ITER. Previous work on disruptions [1] is extended to compute toroidally asymmetric wall force in ITER, using the M3D code. The disruptions are produced by n = 1 resistive wall modes or external kink modes. A thin wall resistive boundary model is used to calculate the wall forces. The symmetric wall force, produced by a VDE, and the asymmetric wall force, produced by n = 1 modes, are comparable in magnitude. It is found that the asymmetric and axisymmetric forces scale with the growth rate of the instability multiplied by the square of the current divided by magnetic field. A similar scaling was reported for VDEs in JET [2]. Numerically, the study of disruptions is very challenging. In the M3D extended MHD code, dealiasing was applied in the toroidal direction. Advection terms were treated with a numerical upwind method. These techniques provided sufficient numerical stability to simulate entire disruption events. [4pt] [1] R. Paccagnella, H. R. Strauss, and J. Breslau, Nucl. Fusion (2009) 49 035003. [2] V. Riccardo, T. C. Hender, P. J. Lomas, et al., Plasma Phys. Control. Fusion (2004)

  3. Network externalities across financial institutions

    OpenAIRE

    Castro Iragorri, Carlos Alberto; Preciado Pua, Sergio Andrés; Ordóñez Herrera, Juan Sebastián

    2016-01-01

    We propose and estimate a financial distress model that explicitly accounts for the interactions or spill-over effects between financial institutions, through the use of a spatial continuity matrix that is build from financial network data of inter bank transactions. Such setup of the financial distress model allows for the empirical validation of the importance of network externalities in determining financial distress, in addition to institution specific and macroeconomic covariates. The re...

  4. Externe Kosten in der Energiewirtschaft

    OpenAIRE

    Voß, Alfred; Friedrich, Rainer

    1994-01-01

    Als externe Effekte werden unbeteiligte Dritte betreffende Zusatzkosten oder Zusatznutzen verstanden, die sich in den jeweiligen Güterpreisen nicht wiederfinden und denen die Betroffenen nicht indifferent gegenüberstehen. Die gegenwärtige Energiebereitstellung und -nutzung ist in vielen Bereichen eine wesentliche Quelle der Belastung von Umwelt und Natur. Begriffe und Schlagworte wie Waldsterben, Tankerunglücke, Tschernobyl und Treibhauseffekt seien in diesem Zusammenhang erwähnt.

  5. Matching Games with Additive Externalities

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal

    2012-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas......, optimistic, and pessimistic behaviour, and provide both computational hardness results and polynomial-time algorithms for computing stable outcomes....

  6. On a character of the forced vibrations of two-layer plate in the second boundary value problem

    Directory of Open Access Journals (Sweden)

    Poghosyan H. M.

    2007-06-01

    Full Text Available The three-dimensional dynamic problem of the elasticity theory on forced vibration of orthotropic plate at coulomb friction between layers is solved by the asymptotic method. The bottom obverse surface is subject to external dynamic influences, and top - is rigidly fixed. The common asymptotic solution of the problem is found. The closed solution for particular type of problems is found. The resonance arising conditions are established. It is known, that constant tangential displacements acting to the second layer do not influence in stress-strain state of the first layer. It is shown, that the same phenomenon with the big accuracy remains in force at linearly varying on coordinates influences.

  7. ENDOSCOPIC DCR VERSUS EXTERNAL DCR

    Directory of Open Access Journals (Sweden)

    Rukma

    2015-04-01

    Full Text Available PURPOSE: To compare success rates of endoscopic dacryocystorhinostomy (DCR and external DCR for acquired nasolacrimal duct obstruction (NLDO. MATERIALS AND METHODS: A prospective comparative non randomized study of 64 patients who presented with acquired NLD obstruction to a tertiary hospital. They were fully evaluated to ascertain the site of obstruction and patients with distal obstruction were included in the study. 34 patients underwent endoscopic DCR and 30 patients underwent external DCR RESULTS: 64 patients were included in the study and 72 procedures carried out. Success was achieved in 65 cases and failure in 7. Of the 7 failed cases, anatomical obstruction at the fistula site was found in 3, whereas functional failure was found in 4. In our patients, endoscopic DCR had a significantly higher success rate than external DCR, 95.23% versus 83.33% (P = 0.03. CONCLUSIONS: The success rate of Endoscopic DCR for acquired NLDO in our group of patients was 95.23%, with endoscopic surgery showing better results.

  8. Conceptual challenges for internalising externalities

    DEFF Research Database (Denmark)

    Miguel, Brandão; Weidema, Bo Pedersen

    2013-01-01

    We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii) The relev......We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii......) The relevance and efficiency of different instruments for internalisation and compensation; and iii) Implementing internalisation over large geographical and temporal distances. We find taxation to be a more relevant and efficient tool for internalisation than insurance and litigation. With increasing...... geographical and especially temporal distance between the benefitting actor and the victim of the external cost, the involvement of a non-governmental intermediate actor becomes increasingly necessary to provide the short-term capital required to ensure a successful implementation....

  9. Individuals' insight into intrapersonal externalities

    Directory of Open Access Journals (Sweden)

    David J. Stillwell

    2012-07-01

    Full Text Available An intrapersonal externality exists when an individual's decisions affect the outcomes of her future decisions. It can result in decreasing or increasing average returns to the rate of consumption, as occurs in addiction or exercise. Experimentation using the Harvard Game, which models intrapersonal externalities, has found differences in decision making between drug users and control subjects, leading to the argument that these externalities influence the course of illicit drug use. Nevertheless, it is unclear how participants who behave optimally conceptualise the problem. We report two experiments using a simplified Harvard Game, which tested the differences in contingency knowledge between participants who chose optimally and participants who did not. Those who demonstrated optimal performance exhibited both a pattern of correct responses and systematic errors to questions about the payoff schedules. The pattern suggested that they learned explicit knowledge of the change in reinforcement on a trail-by-trial basis. They did not have, or need, a full knowledge of the historical interaction leading to each payoff. We also found no evidence of choice differences between participants who were given a guaranteed payment and participants who were paid contingent on their performance, but those given a guaranteed payment were able to report more contingency knowledge as the experiment progressed, suggesting that they explored more rather than settling into a routine. Experiment 2 showed that using a fixed inter-trial interval did not change the results.

  10. Unfolding DNA condensates produced by DNA-like charged depletants: A force spectroscopy study

    Science.gov (United States)

    Lima, C. H. M.; Rocha, M. S.; Ramos, E. B.

    2017-02-01

    In this work, we have measured, by means of optical tweezers, forces acting on depletion-induced DNA condensates due to the presence of the DNA-like charged protein bovine serum albumin (BSA). The stretching and unfolding measurements performed on the semi-flexible DNA chain reveal (1) the softening of the uncondensed DNA contour length and (2) a mechanical behavior strikingly different from those previously observed: the force-extension curves of BSA-induced DNA condensates lack the "saw-tooth" pattern and applied external forces as high as ≈80 pN are unable to fully unfold the condensed DNA contour length. This last mechanical experimental finding is in agreement with force-induced "unpacking" detailed Langevin dynamics simulations recently performed by Cortini et al. on model rod-like shaped condensates. Furthermore, a simple thermodynamics analysis of the unfolding process has enabled us to estimate the free energy involved in the DNA condensation: the estimated depletion-induced interactions vary linearly with both the condensed DNA contour length and the BSA concentration, in agreement with the analytical and numerical analysis performed on model DNA condensates. We hope that future additional experiments can decide whether the rod-like morphology is the actual one we are dealing with (e.g. pulling experiments coupled with super-resolution fluorescence microscopy).

  11. Theoretical model for cellular shapes driven by protrusive and adhesive forces.

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2011-05-01

    Full Text Available The forces that arise from the actin cytoskeleton play a crucial role in determining the cell shape. These include protrusive forces due to actin polymerization and adhesion to the external matrix. We present here a theoretical model for the cellular shapes resulting from the feedback between the membrane shape and the forces acting on the membrane, mediated by curvature-sensitive membrane complexes of a convex shape. In previous theoretical studies we have investigated the regimes of linear instability where spontaneous formation of cellular protrusions is initiated. Here we calculate the evolution of a two dimensional cell contour beyond the linear regime and determine the final steady-state shapes arising within the model. We find that shapes driven by adhesion or by actin polymerization (lamellipodia have very different morphologies, as observed in cells. Furthermore, we find that as the strength of the protrusive forces diminish, the system approaches a stabilization of a periodic pattern of protrusions. This result can provide an explanation for a number of puzzling experimental observations regarding cellular shape dependence on the properties of the extra-cellular matrix.

  12. Frequency and force effects on psychophysical and myoelectric variables in low- intensity pinching tasks

    NARCIS (Netherlands)

    Visser, B.; Dieën, J.H. van; Veeger, D.; Looze, M.P. de; Douwes, M.

    2000-01-01

    Force and frequency in manual handling tasks are known risk factors for work related upper arm disorders. Three force levels and three frequencies are used to define the external load in a pinching task. The effects of these external loads on subjective and objective responses are studied. Subjectiv

  13. The Impact Research of External Social Capital on Performance of New Venture---Acting through Knowledge Acquisition%外部社会资本对新创企业绩效的影响研究--知识获取的中介作用

    Institute of Scientific and Technical Information of China (English)

    鲍盛祥; 陶文庆

    2014-01-01

    基于企业知识理论的观点认为知识资源已成为企业最为重要的战略性资源。外部社会资本作为新创企业社会关系网络在创业活动中的嵌入,是企业知识获取的重要手段。该文以社会资本理论为基础,通过对湖北省内116家新创企业的有效问卷调查及结构方程分析,研究表明,新创企业外部社会资本的结构维度、关系维度、认知维度对知识获取、新创企业绩效有显著影响,知识获取在新创企业外部社会资本与新创企业绩效的关系中起到部分中介作用。因此新创企业应加强外部社会资本构建和管理能力,促进知识获取,从而实现企业绩效的提升。%Knowledge resources has become the most important strategic resource based on the view of enterprise knowledge theory . External social capital as a start -up social network embedded in entrepreneurial activity , is the enterprise important means of knowledge acquisition . Taking social capital theory as foundation , this article analyzed structural equation and questionnaire data of 116 new ventures in Hubei Province . The research results have shown that structural dimensions , relational dimension and cognitive dimensions of external social capital can have remarkable influences on knowledge acquisition as well as new venture performance . Besides , knowledge acquisition plays a part of the intermediary role between external social capital and new venture performance .Therefore ,we hold the attitude that new ventures should strengthen the construction and management of external social capital to accelerate the knowledge acquisition , thereby fully playing a role in promoting enterprise performance .

  14. Axial force measurement for esophageal function testing

    Institute of Scientific and Technical Information of China (English)

    Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  15. Axial force measurement for esophageal function testing.

    Science.gov (United States)

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-14

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  16. Estimation of external contact loads using an inverse dynamics and optimization approach: general method and application to sit-to-stand maneuvers.

    Science.gov (United States)

    Robert, T; Causse, J; Monnier, G

    2013-09-01

    This paper presents a general method to estimate unmeasured external contact loads (ECLs) acting on a system whose kinematics and inertial properties are known. This method is dedicated to underdetermined problems, e.g. when the system has two or more unmeasured external contact wrenches. It is based on inverse dynamics and a quadratic optimization, and is therefore relatively simple, computationally cost effective and robust. Net joint loads (NJLs) are included as variables of the problem, and thus could be estimated in the same procedure as the ECL and be used within the cost function. The proposed method is tested on human sit-to-stand maneuvers performed holding a handle with one hand, i.e. asymmetrical movements with multiples external contacts. Three sets of measured and unmeasured contact load components and three cost functions are considered and simulated results are compared to experimental data. For the population and movement studied, better results are obtained for a least-square sharing between actuated degrees-of-freedom of the relative motor torques (motor torques normalized by the maximal torque production capacity). Moreover, the number of unknown ECL components does not significantly influence the results. In particular, measuring only the vertical force under the seat lead to a relatively correct estimation of the ECL and NJT: not only the values of R% were small (about 10% for the feet ECL and 20% for the NJT), but the influence of an experimental parameters (the Seat Height) was also correctly predicted.

  17. The Dutch Euthanasia Act: recent legal developments.

    Science.gov (United States)

    Legemaate, Johan; Bolt, Ineke

    2013-12-01

    The Dutch Termination of Life on Request and Assisted Suicide Act [Wet toetsing levensbeëindiging op verzoek en hulp bij zelfdoding (Wtl)] came into force in 2002. Its aim is to increase the degree of due care exercised by physicians when terminating a patient's life and to provide a legal framework within which physicians account for their actions in such cases. On the basis of the second evaluation of the Act, published in December 2012, this article provides an overview of the most recent legal developments regarding the Dutch Euthanasia Act. Special attention is given to patients with dementia, psychiatric patients and patient who are "weary of life".

  18. A bidirectional brain-machine interface algorithm that approximates arbitrary force-fields.

    Directory of Open Access Journals (Sweden)

    Alessandro Vato

    Full Text Available We examine bidirectional brain-machine interfaces that control external devices in a closed loop by decoding motor cortical activity to command the device and by encoding the state of the device by delivering electrical stimuli to sensory areas. Although it is possible to design this artificial sensory-motor interaction while maintaining two independent channels of communication, here we propose a rule that closes the loop between flows of sensory and motor information in a way that approximates a desired dynamical policy expressed as a field of forces acting upon the controlled external device. We previously developed a first implementation of this approach based on linear decoding of neural activity recorded from the motor cortex into a set of forces (a force field applied to a point mass, and on encoding of position of the point mass into patterns of electrical stimuli delivered to somatosensory areas. However, this previous algorithm had the limitation that it only worked in situations when the position-to-force map to be implemented is invertible. Here we overcome this limitation by developing a new non-linear form of the bidirectional interface that can approximate a virtually unlimited family of continuous fields. The new algorithm bases both the encoding of position information and the decoding of motor cortical activity on an explicit map between spike trains and the state space of the device computed with Multi-Dimensional-Scaling. We present a detailed computational analysis of the performance of the interface and a validation of its robustness by using synthetic neural responses in a simulated sensory-motor loop.

  19. Quantifying Interparticle Forces and Heterogeneity in 3D Granular Materials.

    Science.gov (United States)

    Hurley, R C; Hall, S A; Andrade, J E; Wright, J

    2016-08-26

    Interparticle forces in granular materials are intimately linked to mechanical properties and are known to self-organize into heterogeneous structures, or force chains, under external load. Despite progress in understanding the statistics and spatial distribution of interparticle forces in recent decades, a systematic method for measuring forces in opaque, three-dimensional (3D), frictional, stiff granular media has yet to emerge. In this Letter, we present results from an experiment that combines 3D x-ray diffraction, x-ray tomography, and a numerical force inference technique to quantify interparticle forces and their heterogeneity in an assembly of quartz grains undergoing a one-dimensional compression cycle. Forces exhibit an exponential decay above the mean and partition into strong and weak networks. We find a surprising inverse relationship between macroscopic load and the heterogeneity of interparticle forces, despite the clear emergence of two force chains that span the system.

  20. Thought Experiments on Gravitational Forces

    CERN Document Server

    Lynden-Bell, Donald

    2013-01-01

    Large contributions to the near closure of the Universe and to the acceleration of its expansion are due to the gravitation of components of the stress-energy tensor other than its mass density. To familiarise astronomers with the gravitation of these components we conduct thought experiments on gravity, analogous to the real experiments that our forebears conducted on electricity. By analogy to the forces due to electric currents we investigate the gravitational forces due to the flows of momentum, angular momentum, and energy along a cylinder. Under tension the gravity of the cylinder decreases but the 'closure' of the 3-space around it increases. When the cylinder carries a torque the flow of angular momentum along it leads to a novel helical interpretation of Levi-Civita's external metric and a novel relativistic effect. Energy currents give gravomagnetic effects in which parallel currents repel and antiparallel currents attract, though such effects must be added to those of static gravity. The gravity of...

  1. External foam layers to football helmets reduce head impact severity.

    Science.gov (United States)

    Nakatsuka, Austin S; Yamamoto, Loren G

    2014-08-01

    Current American football helmet design has a rigid exterior with a padded interior. Softening the hard external layer of the helmet may reduce the impact potential of the helmet, providing extra head protection and reducing its use as an offensive device. The objective of this study is to measure the impact reduction potential provided by external foam. We obtained a football helmet with built-in accelerometer-based sensors, placed it on a boxing mannequin and struck it with a weighted swinging pendulum helmet to mimic the forces sustained during a helmet-to-helmet strike. We then applied layers of 1.3 cm thick polyolefin foam to the exterior surface of the helmets and repeated the process. All impact severity measures were significantly reduced with the application of the external foam. These results support the hypothesis that adding a soft exterior layer reduces the force of impact which may be applicable to the football field. Redesigning football helmets could reduce the injury potential of the sport.

  2. Quantifying the synchronizability of externally driven oscillators.

    Science.gov (United States)

    Stefański, Andrzej

    2008-03-01

    This paper is focused on the problem of complete synchronization in arrays of externally driven identical or slightly different oscillators. These oscillators are coupled by common driving which makes an occurrence of generalized synchronization between a driving signal and response oscillators possible. Therefore, the phenomenon of generalized synchronization is also analyzed here. The research is concentrated on the cases of an irregular (chaotic or stochastic) driving signal acting on continuous-time (Duffing systems) and discrete-time (Henon maps) response oscillators. As a tool for quantifying the robustness of the synchronized state, response (conditional) Lyapunov exponents are applied. The most significant result presented in this paper is a novel method of estimation of the largest response Lyapunov exponent. This approach is based on the complete synchronization of two twin response subsystems via additional master-slave coupling between them. Examples of the method application and its comparison with the classical algorithm for calculation of Lyapunov exponents are widely demonstrated. Finally, the idea of effective response Lyapunov exponents, which allows us to quantify the synchronizability in case of slightly different response oscillators, is introduced.

  3. Effect of an external electric field on the propagation velocity of premixed flames

    KAUST Repository

    Sánchez-Sanz, Mario

    2015-01-01

    © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. There have been many experimental investigations into the ability of electric fields to enhance combustion by acting upon ion species present in flames [1]. In this work, we examine this phenomenon using a one-dimensional model of a lean premixed flame under the influence of a longitudinal electric field. We expand upon prior two-step chain-branching reaction laminar models with reactions to model the creation and consumption of both a positively-charged radical species and free electrons. Also included are the electromotive force in the conservation equation for ion species and the electrostatic form of the Maxwell equations in order to resolve ion transport by externally applied and internally induced electric fields. The numerical solution of these equations allows us to compute changes in flame speed due to electric fields. Further, the variation of key kinetic and transport parameters modifies the electrical sensitivity of the flame. From changes in flame speed and reactant profiles we are able to gain novel, valuable insight into how and why combustion can be controlled by electric fields.

  4. Force distribution in a semiflexible loop

    CERN Document Server

    Waters, James T

    2016-01-01

    Loops undergoing thermal fluctuations are prevalent in nature. Ring-like or cross-linked polymers, cyclic macromolecules, and protein-mediated DNA loops all belong to this category. Stability of these molecules are generally described in terms of free energy, an average quantity, but it may also be impacted by local fluctuating forces acting within these systems. The full distribution of these forces can thus give us insights into mechanochemistry beyond the predictive capability of thermodynamics. In this paper, we study the force exerted by an inextensible semiflexible polymer constrained in a looped state. By using a novel simulation method termed "phase-space sampling", we generate the equilibrium distribution of chain conformations in both position and momentum space. We compute the constraint forces between the two ends of the loop in this chain ensemble using Lagrangian mechanics, and show that the mean of these forces is equal to the thermodynamic force. By analyzing kinetic and potential contribution...

  5. Skepticism, Contextualism, Externalism and Modality

    Directory of Open Access Journals (Sweden)

    Ron Wilburn

    2006-12-01

    Full Text Available In this paper, I argue for the following claims. Contextualist strategies to tame or localize epistemic skepticism are hopeless if contextualist factors are construed internalistically. However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated. While these claims do not give us an argument for skepticism, they do give us an argument that contextualism, as such, is not likely to provide us with an argument against skepticism.

  6. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    own specific set of mechanisms and conditions. Integrating innovations has been mostly studied from an absorptive capacity perspective, with less attention given to the impact of competencies and culture (including “not invented here”). Commercializing innovations puts the most emphasis on how......” in a way inconsistent with earlier definitions in innovation management. The paper concludes with recommendations for future research that include examining the end-to-end innovation commercialization process, and studying the moderators and limits of leveraging external sources of innovation....

  7. Transverse Force on Quarks in DIS

    CERN Document Server

    Burkardt, Matthias

    2015-01-01

    Generalized Parton Distributions (GPDs) provide information on the distribution of quarks in impact paarmeter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. %The strength of that force can be related to twist-3 PDFs. This force when acting along the whole trajectory of the active quark leads to a transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark Orbital Angular Momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.

  8. Theoretical analysis of natural frequency of externally prestressed concrete beam based on rigidity correction

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase with the increase in the prestressing force at the tensioning stage, and the natural frequencies decrease after the cracks occur in the beams. Following the calculation formula of natural frequency of externally prestressed beam, which was reported in a literature, the natural frequencies of the...

  9. Novel Rigid External Distraction Device Improves Stability and Controls the Vector During Midfacial Advancement.

    Science.gov (United States)

    Resnick, Cory M; Rottgers, Stephen Alex; Langenfeld, Christopher C; Mulliken, John B; Padwa, Bonnie L

    2016-06-01

    The major limitation of the rigid external devices currently used for midfacial distraction after subcranial Le Fort III osteotomies is the ductile wire that connects the midface to the device, which makes it difficult to control the vector and force during distraction. The authors describe a novel external appliance that addresses this and other problems of contemporary devices, and application of a custom cranial template that facilitates precise placement of the device to achieve the planned vector of distraction.

  10. Force distribution in a semiflexible loop

    Science.gov (United States)

    Waters, James T.; Kim, Harold D.

    2017-01-01

    Loops undergoing thermal fluctuations are prevalent in nature. Ringlike or cross-linked polymers, cyclic macromolecules, and protein-mediated DNA loops all belong to this category. Stability of these molecules are generally described in terms of free energy, an average quantity, but it may also be impacted by local fluctuating forces acting within these systems. The full distribution of these forces can thus give us insights into mechanochemistry beyond the predictive capability of thermodynamics. In this paper, we study the force exerted by an inextensible semiflexible polymer constrained in a looped state. By using a simulation method termed “phase-space sampling,” we generate the equilibrium distribution of chain conformations in both position and momentum space. We compute the constraint forces between the two ends of the loop in this chain ensemble using Lagrangian mechanics, and show that the mean of these forces is equal to the thermodynamic force. By analyzing kinetic and potential contributions to the forces, we find that the mean force acts in the direction of increasing extension not because of bending stress, but in spite of it. Furthermore, we obtain a distribution of constraint forces as a function of chain length, extension, and stiffness. Notably, increasing contour length decreases the average force, but the additional freedom allows fluctuations in the constraint force to increase. The force distribution is asymmetric and falls off less sharply than a Gaussian distribution. Our work exemplifies a system where large-amplitude fluctuations occur in a way unforeseen by a purely thermodynamic framework, and offers computational tools useful for efficient, unbiased simulation of a constrained system. PMID:27176436

  11. Glenohumeral contact forces and muscle forces evaluated in wheelchair-related activities of daily living in able-bodied subjects versus subjects with paraplegia and tetraplegia

    NARCIS (Netherlands)

    van Drongelen, S; van der Woude, LH; Janssen, Thomas W. J.; Angenot, EL; Chadwick, EK; Veeger, DirkJan (H. E. J.)

    Objective: To estimate the differences in glenohumeral contact forces and shoulder muscle forces between able-bodied subjects and subjects with paraplegia and tetraplegia during wheelchair-related activities of daily living (ADLs). Design: Kinematics and external forces were measured during

  12. Glenohumeral contact forces and muscle forces evaluated in wheelchair-related activities of daily living in able-bodied subjects versus subjects with paraplegia and tetraplegia

    NARCIS (Netherlands)

    van Drongelen, S; van der Woude, LH; Janssen, Thomas W. J.; Angenot, EL; Chadwick, EK; Veeger, DirkJan (H. E. J.)

    2005-01-01

    Objective: To estimate the differences in glenohumeral contact forces and shoulder muscle forces between able-bodied subjects and subjects with paraplegia and tetraplegia during wheelchair-related activities of daily living (ADLs). Design: Kinematics and external forces were measured during wheelcha

  13. Steady State Convergence Acceleration of the Generalized Lattice Boltzmann Equation with Forcing Term through Preconditioning

    CERN Document Server

    Premnath, Kannan N; Banerjee, Sanjoy

    2008-01-01

    Several applications exist in which lattice Boltzmann methods (LBM) are used to compute stationary states of fluid motions, particularly those driven or modulated by external forces. Standard LBM, being explicit time-marching in nature, requires a long time to attain steady state convergence, particularly at low Mach numbers due to the disparity in characteristic speeds of propagation of different quantities. In this paper, we present a preconditioned generalized lattice Boltzmann equation (GLBE) with forcing term to accelerate steady state convergence to flows driven by external forces. The use of multiple relaxation times in the GLBE allows enhancement of the numerical stability. Particular focus is given in preconditioning external forces, which can be spatially and temporally dependent. In particular, correct forms of moment-projections of source/forcing terms are derived such that they recover preconditioned Navier-Stokes equations with non-uniform external forces. As an illustration, we solve an extende...

  14. Quantum Electrodynamics on background external fields

    CERN Document Server

    Marecki, P

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  15. 46 CFR 154.452 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false External pressure. 154.452 Section 154.452 Shipping... Independent Tank Type C and Process Pressure Vessels § 154.452 External pressure. The design external pressure...) for tanks without a vacuum relief valve. P2=0, or the pressure relief valve setting for an enclosed...

  16. 46 CFR 64.19 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false External pressure. 64.19 Section 64.19 Shipping COAST... HANDLING SYSTEMS Standards for an MPT § 64.19 External pressure. (a) A tank without a vacuum breaker must be designed to withstand an external pressure of 71/2 psig or more. (b) A tank with a vacuum breaker...

  17. 49 CFR 195.108 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External pressure. 195.108 Section 195.108 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Design Requirements § 195.108 External pressure. Any external pressure that will be exerted on the...

  18. Quantum electrodynamics on background external fields

    OpenAIRE

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  19. Reciprocity Theorems for Ab Initio Force Calculations

    CERN Document Server

    Wei, C; Mele, E J; Rappe, A M; Lewis, Steven P.; Rappe, Andrew M.

    1996-01-01

    We present a method for calculating ab initio interatomic forces which scales quadratically with the size of the system and provides a physically transparent representation of the force in terms of the spatial variation of the electronic charge density. The method is based on a reciprocity theorem for evaluating an effective potential acting on a charged ion in the core of each atom. We illustrate the method with calculations for diatomic molecules.

  20. Dynamical performance for science-mode stationkeeping with an external occulter

    DEFF Research Database (Denmark)

    Sirbu, Dan; Karsten, Christian Vad; Kasdin, N Jeremy

    2010-01-01

    with fourth-body and solar radiation pressure acting as disturbing forces. An optimal observation window is defined in terms of both thrust required and the Sun-constellation geometry. By simulation, the effects of the stellar latitude and distance, the spacecraft separation, the magnitude of the disturbing...... forces, and...

  1. Key External Influences Affecting Consumers’ Decisions Regarding Food

    Science.gov (United States)

    Martínez-Ruiz, María Pilar; Gómez-Cantó, Carmen María

    2016-01-01

    Among the numerous internal and external forces that compete for consumers’ attention in the context in which they buy their food, this paper will seek to provide a review of the most important external influences, such as the variables related to food itself. To this end, in addition to the food attributes traditionally identified in fields such as consumer behavior, it will give special consideration to the classification of food values. Although the influence of these variables on consumer decisions depends on the individual, analyzing them will undoubtedly increase understanding of consumers’ decisions. Additionally, identifying and describing these variables will enable subsequent research on how they influence both consumer behavior and other key outcomes for producers, manufacturers, and retailers in the food industry, such as satisfaction, trust, and loyalty. PMID:27803686

  2. The Internal and External Constraints on Foreign Policy in India

    DEFF Research Database (Denmark)

    Schmidt, Johannes Dragsbæk

    2017-01-01

    but there is no conclusive evidence in the literature to decide what determines what. There are important dynamics and interplays across the thin line between the domestic and international sphere especially in terms of understanding the reciprocal challenges related to how factors of culture and ethnicity relate...... with the legitimacy of the state. The aim of the paper serves four purposes. To unpack and give a critical overview of the debates concerned with the internal and external aspects of India’s foreign policy; situate the literature dealing more specifically with domestic issues related to culture and ethnicity......The main argument of this contribution is that the distinction between internal and external is at best blurred and in reality does not make much sense in the case of India’s foreign policy. It may start and end at the border and be determined by negotiations, diplomacy or brute force...

  3. Magnetic response to applied electrostatic field in external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, T.C. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); University of Florida, Department of Physics, Gainesville, FL (United States); Gitman, D.M. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Shabad, A.E. [P. N. Lebedev Physics Institute, Moscow (Russian Federation)

    2014-04-15

    We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to the simple example of a spherically symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space; the pattern of the lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics. (orig.)

  4. Magnetic response to applied electrostatic field in external magnetic field

    CERN Document Server

    Adorno, T C; Shabad, A E

    2014-01-01

    We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to a simple example of a spherically-symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space, the pattern of lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics.

  5. Modeling of ribosome dynamics on a ds-mRNA under an external load

    Science.gov (United States)

    Shakiba, Bahareh; Dayeri, Maryam; Mohammad-Rafiee, Farshid

    2016-07-01

    Protein molecules in cells are synthesized by macromolecular machines called ribosomes. According to the recent experimental data, we reduce the complexity of the ribosome and propose a model to express its activity in six main states. Using our model, we study the translation rate in different biological relevant situations in the presence of external force and the translation through the RNA double stranded region in the absence or presence of the external force. In the present study, we give a quantitative theory for translation rate and show that the ribosome behaves more like a Brownian Ratchet motor. Our findings could shed some light on understanding behaviors of the ribosome in biological conditions.

  6. Modeling of Ribosome Dynamics on a ds-mRNA under an External Load

    CERN Document Server

    Shakiba, Bahareh; Mohammad-Rafiee, Farshid

    2016-01-01

    Protein molecules in cells are synthesized by macromolecular machines called ribosomes. According to recent experimental data, we reduce the complexity of the ribosome and propose a model to express its activity in six main states. Using our model, we study the translation rate in different biological relevant situations in the presence of external force, and translation through the RNA double stranded region in the absence or presence of the external force. In the present study, we give a quantitative theory for translation rate and show that the ribosome behaves more like a Brownian Ratchet motor. Our findings could shed some light on understanding behaviors of the ribosome in biological conditions.

  7. Analytical and Numerical Studies for Chaotic Dynamics of a Duffing Oscillator with a Parametric Force

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The chaotic dynamics of a Duffing oscillator with a parametric force is investigated. By using the direct perturbation technique, we analytically obtain the general solution of the 1st-order equation. Through the boundedness condition of the general solution we get the famous Melnikov function predicting the onset of chaos. When the parametric and external forces are strong, numerical simulations show that increasing the amplitude of the parametric or external force can lead the system into chaos via period doubling.

  8. Increased jump height with an external focus due to enhanced lower extremity joint kinetics.

    Science.gov (United States)

    Wulf, Gabriele; Dufek, Janet S

    2009-10-01

    Individuals jump higher when they adopt an external focus of attention, relative to an internal focus or no focus of attention (G. Wulf, T. Zachry, C. Granados, & J. S. Dufek, 2007). In the present study, the authors determined the underlying cause of this effect. Participants performed a vertical jump-and-reach task for (a) an external focus condition (i.e., participants focused on the rungs of a Vertec [Perform Better, Cranston, RI] measurement device that they touched) and (b) an internal focus condition (i.e., participants focused on the finger with which they touched the rungs). Participants' jump height, center-of-mass displacement, jump impulse, and lower extremity joint moments were greater with an external focus compared with an internal focus. These results suggest that participants jump higher by producing greater forces when they adopt an external focus. This finding adds to evidence that an external focus facilitates the production of effective and efficient movement patterns.

  9. DETERMINATION OF BALL COHESIVE AND FRICTIONAL FORCES WITH TOOL AT POLISHING BETWEEN ALIGNED RINGS AND DISK

    Directory of Open Access Journals (Sweden)

    K. G. Schetnikovich

    2010-01-01

    Full Text Available The paper provides a design description of a tool used for polishing balls made of brittle materials between bottom driving disk and two rings. An external stationary ring has a ring turning of rectangular profile that helps the ring to be based directly on the balls which are to be polished and take self-aligned position in relation to tool rotation axis.  Forces acting on the balls in the points of contact with the tool with due account of friction against a separator and conditions of ball sliding along ring working surfaces are determined in the paper. Dependence for determination of stationary and driving ring load ratio when balls are sliding along two contact surfaces of the tool is ascertained in the paper. The paper contains recommendations on selection of modes for ball polishing at its initial and finishing stages.

  10. Ankle fusion stability: a biomechanical comparison of external versus internal fixation.

    Science.gov (United States)

    Hoover, Justin R; Santrock, Robert D; James, William C

    2011-04-11

    This biomechanical study compares bimalleolar external fixation to conventional crossed-screw construct in terms of stability and compression for ankle arthrodesis. The goals of the study were to determine which construct is more stable with bending and torsional forces, and to determine which construct achieves more compression.Fourth-generation bone composite tibia and talocalcaneal models were made to 50th percentile anatomic specifications. Fourteen ankle fusion constructs were created with bimalleolar external fixators and 14 with crossed-screw constructs. Ultimate bend, torque, and compression testing were completed on the external fixator and crossed-screw constructs using a multidirectional Materials Testing Machine (MTS Systems Corp, Eden Prairie, Minnesota). Ultimate bend testing revealed a statistically significant difference (P=.0022) with the mean peak load to failure for the external fixator constructs of 973.2 N compared to 612.5 N for the crossed-screw constructs. Ultimate torque testing revealed the mean peak torque to failure for the external fixator construct was 80.2 Nm and 28.1 Nm for the crossed-screw construct, also a statistically significant difference (P=.0001). The compression testing yielded no statistically significant difference (P=.9268) between the average failure force of the external fixator construct (81.6 kg) and the crossed-screw construct (81.2 kg).With increased stiffness in both bending and torsion and comparable compressive strengths, bimalleolar external fixation is an excellent option for tibiotalar ankle arthrodesis.

  11. Photoacoustic radiation force on a microbubble

    Science.gov (United States)

    Erkol, Hakan; Aytac-Kipergil, Esra; Unlu, Mehmet Burcin

    2014-08-01

    We investigate the radiation force on a microbubble due to the photoacoustic wave which is generated by using a pulsed laser. In particular, we focus on the dependence of pulsed laser parameters on the radiation force. In order to do so, we first obtain a new and comprehensive analytical solution to the photoacoustic wave equation based on the Fourier transform for various absorption profiles. Then, we write an expression of the radiation force containing explicit laser parameters, pulse duration, and beamwidth of the laser. Furthermore, we calculate the primary radiation force acting on a microbubble. We show that laser parameters and the position of the microbubble relative to a photoacoustic source have a considerable effect on the primary radiation force. By means of recent developments in laser technologies that render tunability of pulse duration and repetition frequency possible, an adjustable radiation force can be applied to microbubbles. High spatial control of applied force is ensured on account of smaller focal spots achievable by focused optics. In this context, conventional piezoelectric acoustic source applications could be surpassed. In addition, it is possible to increase the radiation force by making source wavelength with the absorption peak of absorber concurrent. The application of photoacoustic radiation force can open a cache of opportunities such as manipulation of microbubbles used as contrast agents and as carrier vehicles for drugs and genes with a desired force along with in vivo applications.

  12. Externally Wetted Ionic Liquid Thruster

    Science.gov (United States)

    Lozano, P.; Martinez-Sanchez, M.; Lopez-Urdiales, J. M.

    2004-10-01

    This paper presents initial developments of an electric propulsion system based on ionic liquid ion sources (ILIS). Propellants are ionic liquids, which are organic salts with two important characteristics; they remain in the liquid state at room temperature and have negligible vapor pressure, thus allowing their use in vacuum. The working principles of ILIS are similar to those of liquid metal ion sources (LMIS), in which a Taylor cone is electrostatically formed at the tip of an externally wetted needle while ions are emitted directly from its apex. ILIS have the advantage of being able to produce negative ions that have similar masses than their positive counterparts with similar current levels. This opens up the possibility of achieving plume electrical neutrality without electron emitters. The possible multiplexing of these emitters is discussed in terms of achievable thrust density for applications other than micro-propulsion.

  13. External symmetry in general relativity

    CERN Document Server

    Cotaescu, I I

    2000-01-01

    We propose a generalization of the isometry transformations to the geometric context of the field theories with spin where the local frames are explicitly involved. We define the external symmetry transformations as isometries combined with suitable tetrad gauge transformations and we show that these form a group which is locally isomorphic with the isometry one. We point out that the symmetry transformations that leave invariant the equations of the fields with spin have generators with specific spin terms which represent new physical observables. The examples we present are the generators of the central symmetry and those of the maximal symmetries of the de Sitter and anti-de Sitter spacetimes derived in different tetrad gauge fixings. Pacs: 04.20.Cv, 04.62.+v, 11.30.-j

  14. Malaysia and forced migration

    National Research Council Canada - National Science Library

    Arzura Idris

    2012-01-01

    This paper analyzes the phenomenon of "forced migration" in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants...

  15. Cholesteric elastomers in external mechanical and electric fields

    Science.gov (United States)

    Menzel, Andreas M.; Brand, Helmut R.

    2007-01-01

    In our studies, we focus on the reaction of cholesteric side-chain liquid single-crystal elastomers (SCLSCEs) to static external mechanical and electric fields. By means of linearized continuum theory, different geometries are investigated: The mechanical forces are oriented in a direction either parallel or perpendicular to the axis of the cholesteric helix such that they lead to a compression or dilation of the elastomer. Whereas only a homogeneous deformation of the system is found for the parallel case, perpendicularly applied mechanical forces cause either twisting or untwisting of the cholesteric helix. This predominantly depends on the direction in which the director of the cholesteric phase is anchored at the boundaries of the elastomer, and on the sign of a material parameter that describes how deformations of the elastomer couple to the relative rotations between the elastomer and the director. It is also this material parameter that leads to an anisotropy of the mechanical reaction of the system to compression and dilation, due to the liquid crystalline order. The effect of an external electric field is studied when applied parallel to the helix axis of a perfect electric insulator. Here an instability arises at a threshold value of the field amplitude, where the latter results from a competition between the effects of the external electric field on the one hand and the influences of the boundaries of the system, the cholesteric order, and the coupling between the director and the polymer network on the other hand. The instability is either homogeneous in space in the directions perpendicular to the external electric field and includes homogeneous shearing, or, for certain values of the material parameters, there arise undulations of the elastomer and the director orientation perpendicular to the direction of the external electric field at onset. This describes a qualitatively new phenomenon not observed in cholesteric systems yet, as these undulations

  16. Injuries of the external ear.

    Science.gov (United States)

    Templer, J; Renner, G J

    1990-10-01

    Ear injuries occur in people of all ages but predominate in active people such as wrestlers, boxers, and bike riders. The types and extent of injury are a function of the force causing the injury. Shearing forces of moderate intensity cause hematoma formation, whereas greater force causes lacerations or even amputation. Sharp objects cause lacerations determined by the force, direction, and point of impact. The high ratio of surface area to mass makes the auricle vulnerable to extremes of temperature. People participating in high-risk activities should wear protective headgear. The goal of treatment is to restore the normal contours while preventing infection. Hematoma results in disfigurement by organization or chondritis. Evacuation and pressure dressings using sterile technique correct the condition. Second-degree burns are treated by regular cleansing and application of topical antimicrobials. Deeper burns require debridement, biologic dressings, or burying the cartilage subcutaneously for later reconstruction. Simple lacerations are closed under aseptic technique using either skin-to-skin sutures only or sutures of the skin combined with intercartilage sutures. Extensive and complex lacerations require meticulous care to match all fragments and prevent infection or loss of tissue. Bare cartilage must be covered with vascularized tissue. The treatment of total amputation is controversial. Some advocate reattachment as a composite graft using intravenous low molecular weight dextrans and heparin as adjuvants. Mladick dermabrades the amputated pinna, reattaches it with sutures, and then slips it into a pocket of elevated postauricular skin for 2 weeks. Others urge microvascular reanastomosis of the small nutrient vessels. Brent and Byrd separate the cartilage from its overlying skin and envelope it first with vascularized temporoparietal fascia and then a split-thickness skin graft. Chondritis is the most feared complication of injury or surgery of the pinna. It

  17. Handbook of force transducers

    CERN Document Server

    Stefanescu, Dan Mihai

    2011-01-01

    Part I introduces the basic ""Principles and Methods of Force Measurement"" acording to a classification into a dozen of force transducers types: resistive, inductive, capacitive, piezoelectric, electromagnetic, electrodynamic, magnetoelastic, galvanomagnetic (Hall-effect), vibrating wires, (micro)resonators, acoustic and gyroscopic. Two special chapters refer to force balance techniques and to combined methods in force measurement. Part II discusses the ""(Strain Gauge) Force Transducers Components"", evolving from the classical force transducer to the digital / intelligent one, with the inco

  18. Malaysia and forced migration

    OpenAIRE

    Arzura Idris

    2012-01-01

    This paper analyzes the phenomenon of “forced migration” in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysi...

  19. Autism: Why Act Early?

    Science.gov (United States)

    ... What's this? Submit Button Past Emails CDC Features Autism: Why Act Early? Language: English Español (Spanish) Recommend ... helped the world make sense." Florida teenager with Autism Spectrum Disorder "Because my parents acted early, I ...

  20. The Role of the Right Hemisphere in Speech Act Comprehension

    Science.gov (United States)

    Holtgraves, Thomas

    2012-01-01

    In this research the role of the RH in the comprehension of speech acts (or illocutionary force) was examined. Two split-screen experiments were conducted in which participants made lexical decisions for lateralized targets after reading a brief conversation remark. On one-half of the trials the target word named the speech act performed with the…

  1. The Social Support Act: the story so far

    NARCIS (Netherlands)

    Mirjam de Klerk; Rob Gilsing; Joost Timmermans

    2010-01-01

    Original title: Op weg met de Wmo. The Social Support Act (Wet maatschappelijke ondersteuning - Wmo) came into force in the Netherlands on 1 January 2007. The aim of the Act is to promote people's social and life skills and ability to participate, and to strengthen social cohesion and quality of li

  2. Applications of Lorentz force in medical acoustics: Lorentz force hydrophone, Lorentz Force Electrical Impedance Tomography, Imaging of shear waves induced by Lorentz force

    CERN Document Server

    Grasland-Mongrain, Pol

    2014-01-01

    The ability of the Lorentz force to link a mechanical displacement to an electrical current presents a strong interest for medical acoustics, and three applications were studied in this thesis. In the first part of this work, a hydrophone was developed for mapping the particle velocity of an acoustic field. This hydrophone was constructed using a thin copper wire and an external magnetic field. A model was elaborated to determine the relationship between the acoustic pressure and the measured electrical current, which is induced by Lorentz force when the wire vibrates in the acoustic field of an ultrasound transducer. The built prototype was characterized and its spatial resolution, frequency response, sensitivity, robustness and directivity response were investigated. An imaging method called Lorentz Force Electrical Impedance Tomography was also studied. In this method, a biological tissue is vibrated by ultrasound in a magnetic field, which induces an electrical current by Lorentz force. The electrical imp...

  3. FORCE OPTIMIZATION OF GRASPING BY ROBOTIC HANDS

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    It is important for robotic hands to obtain optimal grasping performance in the meanwhile balancing external forces and maintaining grasp stability.The problem of force optimization of grasping is solved in the space of joint torques.A measure of grasping performance is presented to protect joint actuators from working in heavy payloads.The joint torques are calculated for the optimal performance under the frictional constraints and the physical limits of motor outputs.By formulating the grasping forces into the explicit function of joint torques, the frictional constraints imposed on the grasping forces are transformed into the constraints on joint torques.Without further simplification, the nonlinear frictional constraints can be simply handled in the process of optimization.Two numerical examples demonstrate the simplicity and effectiveness of the approach.

  4. Effect of the External Lubrication Method for a Rotary Tablet Press on the Adhesion of the Film Coating Layer.

    Science.gov (United States)

    Kondo, Hisami; Toyota, Hiroyasu; Kamiya, Takayuki; Yamashita, Kazunari; Hakomori, Tadashi; Imoto, Junko; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2017-01-01

    External lubrication is a useful method which reduces the adhesion of powder to punches and dies by spraying lubricants during the tableting process. However, no information is available on whether the tablets prepared using an external lubrication system can be applicable for a film coating process. In this study, we evaluated the adhesion force of the film coating layer to the surface of tablets prepared using an external lubrication method, compared with those prepared using internal lubrication method. We also evaluated wettability, roughness and lubricant distribution state on the tablet surface before film coating, and investigated the relationship between peeling of the film coating layer and these tablet surface properties. Increasing lubrication through the external lubrication method decreased wettability of the tablet surface. However, no change was observed in the adhesion force of the film coating layer. On the other hand, increasing lubrication through the internal lubrication method, decreased both wettability of the tablet surface and the adhesion force of the film coating layer. The magnesium stearate distribution state on the tablet surface was assessed using an X-ray fluorescent analyzer and lubricant agglomerates were observed in the case of the internal lubrication method. However, the lubricant was uniformly dispersed in the external lubrication samples. These results indicate that the distribution state of the lubricant affects the adhesion force of the film coating layer, and external lubrication maintained sufficient lubricity and adhesion force of the film coating layer with a small amount of lubricant.

  5. The dermatology acting internship.

    Science.gov (United States)

    Stephens, John B; Raimer, Sharon S; Wagner, Richard F

    2011-07-15

    Acting internships are an important component of modern day medical school curriculum. Several specialties outside of internal medicine now offer acting internship experiences to fourth year medical students. We have found that a dermatology acting internship is a valuable experience for fourth year medical students who are interested in pursuing a residency in dermatology. Our experience with the dermatology acting internship over the 2010-2011 academic year is described.

  6. 78 FR 14295 - Privacy Act of 1974; System of Records

    Science.gov (United States)

    2013-03-05

    ... submitting comments. * Mail: Federal Docket Management System Office, 4800 Mark Center Drive East Tower, 2nd... have been identified as being absent without leave or deserter.'' Categories of records in the system... Department of the Air Force Privacy Act of 1974; System of Records AGENCY: Department of the Air Force,...

  7. New mitral annular force transducer optimized to distinguish annular segments and multi-plane forces.

    Science.gov (United States)

    Skov, Søren Nielsen; Røpcke, Diana Mathilde; Ilkjær, Christine; Rasmussen, Jonas; Tjørnild, Marcell Juan; Jimenez, Jorge H; Yoganathan, Ajit P; Nygaard, Hans; Nielsen, Sten Lyager; Jensen, Morten Olgaard

    2016-03-21

    Limited knowledge exists about the forces acting on mitral valve annuloplasty repair devices. The aim of this study was to develop a new mitral annular force transducer to measure the forces acting on clinically used mitral valve annuloplasty devices. The design of an X-shaped transducer in the present study was optimized for simultaneous in- and out-of-plane force measurements. Each arm was mounted with strain gauges on four circumferential elements to measure out-of-plane forces, and the central parts of the X-arms were mounted with two strain gauges to measure in-plane forces. A dedicated calibration setup was developed to calibrate isolated forces with tension and compression for in- and out-of-plane measurements. With this setup, it was possible with linear equations to isolate and distinguish measured forces between the two planes and minimize transducer arm crosstalk. An in-vitro test was performed to verify the crosstalk elimination method and the assumptions behind it. The force transducer was implanted and evaluated in an 80kg porcine in-vivo model. Following crosstalk elimination, in-plane systolic force accumulation was found to be in average 4.0±0.1N and the out-of-plane annular segments experienced an average force of 1.4±0.4N. Directions of the systolic out-of-plane forces indicated movements towards a saddle shaped annulus, and the transducer was able to measure independent directional forces in individual annular segments. Further measurements with the new transducer coupled with clinical annuloplasty rings will provide a detailed insight into the biomechanical dynamics of these devices.

  8. Laboratory experiment for the study of friction forces using rotating apparatus

    Science.gov (United States)

    Kladivová, Mária; Kovaľaková, Mária; Gibová, Zuzana; Fričová, Oľga; Hutníková, Mária; Kecer, Ján

    2016-11-01

    The standard experimental set-up enabling observation of rotational motion of a bar around its centre of mass, which is set into motion due to the external torque generated by the small weight, was extended with an optical gate and position sensor and connected to a computer with software, which made it possible to display measured values of bar half-rotations during accelerated and decelerated motion as well as to process the data immediately. The detailed analysis of experimental data obtained for decelerated rotational motion due to frictional torque only (without small weight) showed that, besides the constant term due to dry friction at an axle, the expression for friction forces in the system has to include terms depending on the first and/or second power of angular speed, which is evidence that viscous forces influence the motion of a bar. The frictional torque due to viscous forces can be evaluated as the difference between the effective frictional torque acting on the system and the frictional torque due to dry friction at an axle. The data obtained in the experiment in which the bar performed damped oscillatory motion provided the values of effective frictional torque and the moment of inertia of rotating bodies. The frictional torque due to dry friction can be obtained as a minimum torque (calculated using minimum mass of weight) needed to start rotational motion. The last two proposed experiments can be included in undergraduate laboratory practicals.

  9. BEARING FORCES OF EMERGENCY GATE DURING SHUTOFF

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    For an emergency gate in a surge tank, forces acting on the gate were systematically tested and analyzed, including pulling forces resulted from water hammer because of the sudden rejection of all loads in turbine units under different gate levels, and forces during the process of gate shutoff under the conditions of different number of running turbine units. Besides, for the pulling force on the top of gate, their variation processes with time and extent of gate opening were also tested. It is shown that the calculated value of gate pulling force agrees on the whole with the tested one. The results indicate that the emergency gate in the extraordinary large surge tank of WWS hydropower station is safe under the above testing conditions. The related data in the present paper are helpful for the study on an emergency in a sure tank.

  10. 76 FR 60863 - Aquatic Nuisance Species Task Force Meeting

    Science.gov (United States)

    2011-09-30

    ... location is accessible to wheelchair users. If you require additional accommodations, please notify us at...-Chair, Aquatic Nuisance Species Task Force, Acting Assistant Director--Fisheries and Habitat...

  11. Magnus and other forces on vortices in superfluids and superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Michael [University of Illinois, IL (United States)

    1998-07-01

    I discuss some of the forces acting on vortices in charged superfluids, paying particular attention to the way that the Berry and Aharonov-Casher phases combine to reflect the classical magnetohydrodynamics. (Author). 28 refs.

  12. Adhesion Force Measurements Using an Atomic Force Microscope Upgraded with a Linear Position Sensitive Detector

    Science.gov (United States)

    Pierce, M.; Stuart, J.; Pungor, A.; Dryden, P.

    2012-01-01

    The atomic force microscope (AFM), in addition to providing images on an atomic scale, can be used to measure the forces between surfaces and the AFM probe. The potential uses of mapping the adhesive forces on the surface include a spatial determination of surface energy and a direct identification of surface proteins through specific protein–ligand binding interactions. The capabilities of the AFM to measure adhesive forces can be extended by replacing the four-quadrant photodiode detection sensor with an external linear position sensitive detector and by utilizing a dedicated user-programmable signal generator and acquisiton system. Such an upgrade enables the microscope to measure in the larger dynamic range of adhesion forces, improves the sensitivity and linearity of the measurement, and eliminates the problems inherent to the multiple repetitious contacts between the AFM probe and the specimen surface. PMID:25125792

  13. Friction Force: From Mechanics to Thermodynamics

    Science.gov (United States)

    Ferrari, Christian; Gruber, Christian

    2010-01-01

    We study some mechanical problems in which a friction force is acting on a system. Using the fundamental concepts of state, time evolution and energy conservation, we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws of thermodynamics and then apply them to investigate the time evolution and heat transfer of…

  14. Archimedes force on Casimir apparatus

    Science.gov (United States)

    Shevchenko, V.; Shevrin, E.

    2016-11-01

    The talk addresses a problem of Casimir apparatus in weak gravitational field, surrounded by a dense medium. The falling of the apparatus has to be governed by the equivalence principle, taking into account proper contributions to the weight of the apparatus from its material part and from distorted quantum fields. We discuss general ex pression for the corresponding force in terms of the effective action. By way of example we compute explicit expression for Archimedes force, acting on the Casimir apparatus of finite size, immersed into thermal bath of free scalar field. It is shown that besides universal term, proportional to the volume of the apparatus, there are non-universal quantum corrections, depending on the boundary conditions.

  15. Archimedes force on Casimir apparatus

    Directory of Open Access Journals (Sweden)

    Shevchenko V.

    2016-01-01

    Full Text Available The talk addresses a problem of Casimir apparatus in weak gravitational field, surrounded by a dense medium. The falling of the apparatus has to be governed by the equivalence principle, taking into account proper contributions to the weight of the apparatus from its material part and from distorted quantum fields. We discuss general ex pression for the corresponding force in terms of the effective action. By way of example we compute explicit expression for Archimedes force, acting on the Casimir apparatus of finite size, immersed into thermal bath of free scalar field. It is shown that besides universal term, proportional to the volume of the apparatus, there are non-universal quantum corrections, depending on the boundary conditions.

  16. Vorticity from irrotationally forced flow

    CERN Document Server

    Del Sordo, Fabio

    2010-01-01

    In the interstellar medium the turbulence is believed to be forced mostly through supernova explosions. In a first approximation these flows can be written as a gradient of a potential being thus devoid of vorticity. There are several mechanisms that could lead to vorticity generation, like viscosity and baroclinic terms, rotation, shear and magnetic fields, but it is not clear how effective they are, neither is it clear whether the vorticity is essential in determining the turbulent diffusion acting in the ISM. Here we present a study of the role of rotation, shear and baroclinicity in the generation of vorticity in the ISM.

  17. Minimum Normal Force Principle Based Quantitive Optimizationof Clamping Forces for Thin Walled Part

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fa-ping; SUN Hou-fang; SHAHID I.Butt

    2008-01-01

    Based on the stability criteria of workpiece-fixture system, quantitative optimization of clamping forces during precise machining process for thin walled part is studied considering the contact condition between wokpiece and locator, the contact mechanical model is achieved ,which is further been used to calculate the entire passive forces acting on the statically undetermined workpiece by means of the force screw theory as well as minimum norm force principle. Furthermore, a new methodology to optimize clamping forces is put forward, on the criteria of keeping the stability of workpiece during cutting process. By this way, the intensity of clamping forces is decreased dramatically, which will be most beneficial for improving the machining quality of thin-walled parts. Finally, a case study is used to support and validate the proposed model.

  18. Indirect Speech Acts

    Institute of Scientific and Technical Information of China (English)

    李威

    2001-01-01

    Indirect speech acts are frequently used in verbal communication, the interpretation of them is of great importance in order to meet the demands of the development of students' communicative competence. This paper, therefore, intends to present Searle' s indirect speech acts and explore the way how indirect speech acts are interpreted in accordance with two influential theories. It consists of four parts. Part one gives a general introduction to the notion of speech acts theory. Part two makes an elaboration upon the conception of indirect speech act theory proposed by Searle and his supplement and development of illocutionary acts. Part three deals with the interpretation of indirect speech acts. Part four draws implication from the previous study and also serves as the conclusion of the dissertation.

  19. Locally Bounded Function Spaces as the External Environment for Nonlinear Systems

    Directory of Open Access Journals (Sweden)

    Valery G. Fetisov

    2013-01-01

    Full Text Available . In this paper we consider locally bounded function spaces that act as the external environment for nonlinear dynamic systems. We give non-traditional examples of above spaces in which the basis of the selected function Orlicz space

  20. Piano Students' Conceptions of Musical Scores as External Representations: A Cross-Sectional Study

    Science.gov (United States)

    Bautista, Alfredo; Perez Echeverria, Ma del Puy; Pozo, J. Ignacio; Brizuela, Barbara M.

    2009-01-01

    Musical scores are some of the most important learning tools for musicians' acquisition of musical knowledge. However, despite their educational relevance, very little is known about how music students "conceive" of these cultural external representations. Given that these conceptions might act as mediators of students' learning…