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Sample records for angular velocity

  1. Measuring Average Angular Velocity with a Smartphone Magnetic Field Sensor

    Science.gov (United States)

    Pili, Unofre; Violanda, Renante

    2018-01-01

    The angular velocity of a spinning object is, by standard, measured using a device called a tachometer. However, by directly using it in a classroom setting, the activity is likely to appear as less instructive and less engaging. Indeed, some alternative classroom-suitable methods for measuring angular velocity have been presented. In this paper,…

  2. Demonstrating the Direction of Angular Velocity in Circular Motion

    Science.gov (United States)

    Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan

    2015-01-01

    Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics…

  3. The Effects of Isokinetic Strength Training on Strength at Different Angular Velocities: a Pilot Study

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    Tuğba Kocahan

    2017-09-01

    Conclusion: It was shown that angular velocity is important in isokinetic training, and that training at high angular velocities provides strength increases at lower angular velocities, but would not increase strength at angular velocities above the training level. For this reason, it is thought that in the preparation of an isokinetic strength training protocol, angular velocities need to be taken into account. For any athlete, the force at the angular velocity required in her/his sports branch needs to be considered.

  4. Spacecraft Angular Velocity Estimation Algorithm Based on Orientation Quaternion Measurements

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    M. V. Li

    2016-01-01

    Full Text Available The spacecraft (SC mission involves providing the appropriate orientation and stabilization of the associated axes in space. One of the main sources of information for the attitude control system is the angular rate sensor blocks. One way to improve a reliability of the system is to provide a back up of the control algorithms in case of failure of these blocks. To solve the problem of estimation of SP angular velocity vector in the inertial system of coordinates with a lack of information from the angular rate sensors is supposed the use of orientation data from the star sensors; in this case at each clock of the onboard digital computer. The equations in quaternions are used to describe the kinematics of rotary motion. Their approximate solution is used to estimate the angular velocity vector. Methods of modal control and multi-dimensional decomposition of a control object are used to solve the problem of observation and identification of the angular rates. These methods enabled us to synthesize the SP angular velocity vector estimation algorithm and obtain the equations, which relate the error quaternion with the calculated estimate of the angular velocity. Mathematical modeling was carried out to test the algorithm. Cases of different initial conditions were simulated. Time between orientation quaternion measurements and angular velocity of the model was varied. The algorithm was compared with a more accurate algorithm, built on more complete equations. Graphs of difference in angular velocity estimation depending on the number of iterations are presented. The difference in angular velocity estimation is calculated from results of the synthesized algorithm and the algorithm for more accurate equations. Graphs of error distribution for angular velocity estimation with initial conditions being changed are also presented, and standard deviations of estimation errors are calculated. The synthesized algorithm is inferior in accuracy assessment to

  5. Variation in angular velocity and angular acceleration of a particle in rectilinear motion

    International Nuclear Information System (INIS)

    Mashood, K K; Singh, V A

    2012-01-01

    We discuss the angular velocity and angular acceleration associated with a particle in rectilinear motion with constant acceleration. The discussion was motivated by an observation that students and even teachers have difficulty in ascribing rotational motion concepts to a particle when the trajectory is a straight line. We present some details of our observations. A formal derivation of ω and α is presented which reveals ‘surprising’ and non-intuitive aspects, namely non-monotonic behaviour with an associated extremum. The special case of constant velocity is studied and we find that angular acceleration associated with it also has an extremum. We discuss a plausible source of difficulty. (paper)

  6. Alignment of angular velocity sensors for a vestibular prosthesis

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    DiGiovanna Jack

    2012-02-01

    Full Text Available Abstract Vestibular prosthetics transmit angular velocities to the nervous system via electrical stimulation. Head-fixed gyroscopes measure angular motion, but the gyroscope coordinate system will not be coincident with the sensory organs the prosthetic replaces. Here we show a simple calibration method to align gyroscope measurements with the anatomical coordinate system. We benchmarked the method with simulated movements and obtain proof-of-concept with one healthy subject. The method was robust to misalignment, required little data, and minimal processing.

  7. Angular correlations between recoil velocity and angular momentum vectors in molecular photodissociation

    Science.gov (United States)

    Hall, G. E.; Sivakumar, N.; Chawla, D.; Houston, P. L.; Burak, I.

    1988-03-01

    A technique has been developed for determining the angular correlation between a photofragment's angular momentum vector J, its recoil velocity vector v, and the transition dipole moment of the parent molecule μp . Doppler profile spectroscopy used in conjunction with laser-induced fluorescence probing by polarized light can be used to determine the correlations. The pairwise correlations between these vectors as well as their triple correlation are discussed for limiting cases using a classical approach as well as for the general case using a quantum approach based on density matrices. The current formulations differ in two ways from the recent approach of Dixon, who used a bipolar expansion of the correlated velocity and angular momentum distributions. The physical basis for the influence of the vector correlations on the Doppler profile is somewhat more transparent in the current formulations, and the direct connection between the measured correlations and the t-matrix elements occurring in the theory of Balint-Kurti and Shapiro for the photodissociation of a triatomic molecule is also demonstrated.

  8. A Simple Piece of Apparatus to Aid the Understanding of the Relationship between Angular Velocity and Linear Velocity

    Science.gov (United States)

    Unsal, Yasin

    2011-01-01

    One of the subjects that is confusing and difficult for students to fully comprehend is the concept of angular velocity and linear velocity. It is the relationship between linear and angular velocity that students find difficult; most students understand linear motion in isolation. In this article, we detail the design, construction and…

  9. The instantaneous torque-angular velocity relation in plantar flexion during jumping

    NARCIS (Netherlands)

    van Ingen Schenau, G J; Bobbert, M F; Huijing, P A; Woittiez, R D

    Torques, angular velocities, and power of the ankle joint during plantar flexion were measured in jumping experiments in order to achieve insight into shape and magnitude of the instantaneous torque-angular velocity relation in a complex movement. Twelve trained subjects performed maximal vertical

  10. Angular velocity of a spheroid log rolling in a simple shear at small Reynolds number

    Science.gov (United States)

    Meibohm, Jan; Candelier, Fabien; Rosen, Tomas; Einarsson, Jonas; Lundell, Fredrik; Mehlig, Bernhard

    2016-11-01

    We analyse the angular velocity of a small neutrally buoyant spheroid log rolling in a simple shear. When the effect of fluid inertia is negligible the angular velocity ω -> equals half the fluid vorticity. We compute by singular perturbation theory how weak fluid inertia reduces the angular velocity in an unbounded shear, and how this reduction depends upon the shape of the spheroid (on its aspect ratio). In addition we determine the angular velocity by direct numerical simulations. The results are in excellent agreement with the theory at small but not too small values of the shear Reynolds number, for all aspect ratios considered. For the special case of a sphere we find ω / s = - 1 / 2 + 0 . 0540Re 3 / 2 where s is the shear rate and Re is the shear Reynolds number. This result differs from that derived by Lin et al. who obtained a numerical coefficient roughly three times larger.

  11. Angular velocity determination of spinning solar sails using only a sun sensor

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    Kun Zhai

    2017-02-01

    Full Text Available The direction of the sun is the easiest and most reliable observation vector for a solar sail running in deep space exploration. This paper presents a new method using only raw measurements of the sun direction vector to estimate angular velocity for a spinning solar sail. In cases with a constant spin angular velocity, the estimation equation is formed based on the kinematic model for the apparent motion of the sun direction vector; the least-squares solution is then easily calculated. A performance criterion is defined and used to analyze estimation accuracy. In cases with a variable spin angular velocity, the estimation equation is developed based on the kinematic model for the apparent motion of the sun direction vector and the attitude dynamics equation. Simulation results show that the proposed method can quickly yield high-precision angular velocity estimates that are insensitive to certain measurement noises and modeling errors.

  12. A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

    OpenAIRE

    Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

    2015-01-01

    With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage  and temperature  as the input variables and angular velocity error  as the output variable. Firstly, the angular ve...

  13. Brain strain uncertainty due to shape variation in and simplification of head angular velocity profiles.

    Science.gov (United States)

    Zhao, Wei; Ji, Songbai

    2017-04-01

    Head angular velocity, instead of acceleration, is more predictive of brain strains. Surprisingly, no study exists that investigates how shape variation in angular velocity profiles affects brain strains, beyond characteristics such as peak magnitude and impulse duration. In this study, we evaluated brain strain uncertainty due to variation in angular velocity profiles and further compared with that resulting from simplifying the profiles into idealized shapes. To do so, we used reconstructed head impacts from American National Football League for shape extraction and simulated head uniaxial coronal rotations from onset to full stop. The velocity profiles were scaled to maintain an identical peak velocity magnitude and duration in order to isolate the shape for investigation. Element-wise peak maximum principal strains from 44 selected impacts were obtained. We found that the shape of angular velocity profile could significantly affect brain strain magnitude (e.g., percentage difference of 4.29-17.89 % in the whole brain relative to the group average, with cumulative strain damage measure (CSDM) uncertainty range of 23.9 %) but not pattern (correlation coefficient of 0.94-0.99). Strain differences resulting from simplifying angular velocity profiles into idealized shapes were largely within the range due to shape variation, in both percentage difference and CSDM (signed difference of 3.91 % on average, with a typical range of 0-6 %). These findings provide important insight into the uncertainty or confidence in the performance of kinematics-based injury metrics. More importantly, they suggest the feasibility to simplify head angular velocity profiles into idealized shapes, at least within the confinements of the profiles evaluated, to enable real-time strain estimation via pre-computation in the future.

  14. Satellite angular velocity estimation based on star images and optical flow techniques.

    Science.gov (United States)

    Fasano, Giancarmine; Rufino, Giancarlo; Accardo, Domenico; Grassi, Michele

    2013-09-25

    An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components.

  15. Satellite Angular Velocity Estimation Based on Star Images and Optical Flow Techniques

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    Giancarmine Fasano

    2013-09-01

    Full Text Available An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components.

  16. Measuring the Angular Velocity of a Propeller with Video Camera Using Electronic Rolling Shutter

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    Yipeng Zhao

    2018-01-01

    Full Text Available Noncontact measurement for rotational motion has advantages over the traditional method which measures rotational motion by means of installing some devices on the object, such as a rotary encoder. Cameras can be employed as remote monitoring or inspecting sensors to measure the angular velocity of a propeller because of their commonplace availability, simplicity, and potentially low cost. A defect of the measurement with cameras is to process the massive data generated by cameras. In order to reduce the collected data from the camera, a camera using ERS (electronic rolling shutter is applied to measure angular velocities which are higher than the speed of the camera. The effect of rolling shutter can induce geometric distortion in the image, when the propeller rotates during capturing an image. In order to reveal the relationship between the angular velocity and the image distortion, a rotation model has been established. The proposed method was applied to measure the angular velocities of the two-blade propeller and the multiblade propeller. The experimental results showed that this method could detect the angular velocities which were higher than the camera speed, and the accuracy was acceptable.

  17. Angular velocity estimation based on star vector with improved current statistical model Kalman filter.

    Science.gov (United States)

    Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Zhang, He

    2016-11-20

    Angular velocity information is a requisite for a spacecraft guidance, navigation, and control system. In this paper, an approach for angular velocity estimation based merely on star vector measurement with an improved current statistical model Kalman filter is proposed. High-precision angular velocity estimation can be achieved under dynamic conditions. The amount of calculation is also reduced compared to a Kalman filter. Different trajectories are simulated to test this approach, and experiments with real starry sky observation are implemented for further confirmation. The estimation accuracy is proved to be better than 10-4  rad/s under various conditions. Both the simulation and the experiment demonstrate that the described approach is effective and shows an excellent performance under both static and dynamic conditions.

  18. Rotating Hele-Shaw cell with a time-dependent angular velocity

    Science.gov (United States)

    Anjos, Pedro H. A.; Alvarez, Victor M. M.; Dias, Eduardo O.; Miranda, José A.

    2017-12-01

    Despite the large number of existing studies of viscous flows in rotating Hele-Shaw cells, most investigations analyze rotational motion with a constant angular velocity, under vanishing Reynolds number conditions in which inertial effects can be neglected. In this work, we examine the linear and weakly nonlinear dynamics of the interface between two immiscible fluids in a rotating Hele-Shaw cell, considering the action of a time-dependent angular velocity, and taking into account the contribution of inertia. By using a generalized Darcy's law, we derive a second-order mode-coupling equation which describes the time evolution of the interfacial perturbation amplitudes. For arbitrary values of viscosity and density ratios, and for a range of values of a rotational Reynolds number, we investigate how the time-dependent angular velocity and inertia affect the important finger competition events that traditionally arise in rotating Hele-Shaw flows.

  19. A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils

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    Jian Li

    2016-09-01

    Full Text Available Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent “I-shape” is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation.

  20. A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils.

    Science.gov (United States)

    Li, Jian; Wu, Dan; Han, Yan

    2016-09-30

    Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent "I-shape" is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation.

  1. Resolving Two Dimensional Angular Velocity within a Rotary Tumbler

    Science.gov (United States)

    Helminiak, Nathaniel; Helminiak, David; Cariapa, Vikram; Borg, John

    2015-11-01

    In this study, a horizontally oriented cylindrical tumbler, filled at variable depth with cylindrical media, was rotated at various constant speeds. A monoplane layer of media was photographed with a high-speed camera and images were post processed with Particle Tracking Velocimetry (PTV) algorithms in order to resolve both the translational and rotational flow fields. Although the translational velocity fields have been well characterized, contemporary resources enabled the ability to expand upon and refine data regarding rotational characteristics of particles within a rotary tumbler. The results indicate that particles rotate according to intermittent no-slip interactions between the particles and solid body rotation. Particles within the bed, not confined to solid body rotation, exhibited behavior indicative of gearing between particles; each reacting to the tangential component of contact forming rotation chains. Furthermore, it was observed that solid body interactions corresponded to areas of confined motion, as areas of high interaction dissuaded no-slip rotation, while areas of developing flow tended towards no-slip rotation. Special thanks to: NASA Wisconsin Space Grant Consortium Program as well as Marquette University OPUS College of Engineering.

  2. Angular velocity of a sphere in a simple shear at small Reynolds number

    Science.gov (United States)

    Meibohm, J.; Candelier, F.; Rosén, T.; Einarsson, J.; Lundell, F.; Mehlig, B.

    2016-12-01

    We analyze the angular velocity of a small neutrally buoyant spheroid log rolling in a simple shear. When the effect of fluid inertia is negligible the angular velocity ω equals half the fluid vorticity. We compute by singular perturbation theory how weak fluid inertia reduces the angular velocity in an unbounded shear, and how this reduction depends upon the shape of the spheroid (on its aspect ratio). In addition we determine the angular velocity by direct numerical simulations. The results are in excellent agreement with the theory at small but not too small values of the shear Reynolds number Res, for all aspect ratios considered. For the special case of a sphere we find ω /s =-1 /2 +0.0540 Res3 /2 where s is the shear rate. The O (Res3 /2) correction differs from that derived by Lin et al. [J. Fluid Mech. 44, 1 (1970), 10.1017/S0022112070001659], who obtained a numerical coefficient roughly three times larger.

  3. How Angular Velocity Features and Different Gyroscope Noise Types Interact and Determine Orientation Estimation Accuracy

    Science.gov (United States)

    Pasciuto, Ilaria; Ligorio, Gabriele; Bergamini, Elena; Vannozzi, Giuseppe; Sabatini, Angelo Maria; Cappozzo, Aurelio

    2015-01-01

    In human movement analysis, 3D body segment orientation can be obtained through the numerical integration of gyroscope signals. These signals, however, are affected by errors that, for the case of micro-electro-mechanical systems, are mainly due to: constant bias, scale factor, white noise, and bias instability. The aim of this study is to assess how the orientation estimation accuracy is affected by each of these disturbances, and whether it is influenced by the angular velocity magnitude and 3D distribution across the gyroscope axes. Reference angular velocity signals, either constant or representative of human walking, were corrupted with each of the four noise types within a simulation framework. The magnitude of the angular velocity affected the error in the orientation estimation due to each noise type, except for the white noise. Additionally, the error caused by the constant bias was also influenced by the angular velocity 3D distribution. As the orientation error depends not only on the noise itself but also on the signal it is applied to, different sensor placements could enhance or mitigate the error due to each disturbance, and special attention must be paid in providing and interpreting measures of accuracy for orientation estimation algorithms. PMID:26393606

  4. How Angular Velocity Features and Different Gyroscope Noise Types Interact and Determine Orientation Estimation Accuracy

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    Ilaria Pasciuto

    2015-09-01

    Full Text Available In human movement analysis, 3D body segment orientation can be obtained through the numerical integration of gyroscope signals. These signals, however, are affected by errors that, for the case of micro-electro-mechanical systems, are mainly due to: constant bias, scale factor, white noise, and bias instability. The aim of this study is to assess how the orientation estimation accuracy is affected by each of these disturbances, and whether it is influenced by the angular velocity magnitude and 3D distribution across the gyroscope axes. Reference angular velocity signals, either constant or representative of human walking, were corrupted with each of the four noise types within a simulation framework. The magnitude of the angular velocity affected the error in the orientation estimation due to each noise type, except for the white noise. Additionally, the error caused by the constant bias was also influenced by the angular velocity 3D distribution. As the orientation error depends not only on the noise itself but also on the signal it is applied to, different sensor placements could enhance or mitigate the error due to each disturbance, and special attention must be paid in providing and interpreting measures of accuracy for orientation estimation algorithms.

  5. A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

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    Yanshun Zhang

    2015-02-01

    Full Text Available With the open-loop fiber optic gyro (OFOG model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage  and temperature  as the input variables and angular velocity error  as the output variable. Firstly, the angular velocity error  is extracted from OFOG output signals, and then the output voltage , temperature  and angular velocity error  are used as the learning samples to train a Radial-Basis-Function (RBF neural network model. Then the nonlinear mapping model over T,  and  is established and thus  can be calculated automatically to compensate OFOG errors according to  and . The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by ,  and  relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by ,  and , respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity.

  6. A new open-loop fiber optic gyro error compensation method based on angular velocity error modeling.

    Science.gov (United States)

    Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

    2015-02-27

    With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage u and temperature T as the input variables and angular velocity error Δω as the output variable. Firstly, the angular velocity error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular velocity error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network model. Then the nonlinear mapping model over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.42%, respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity.

  7. Test-retest reliability of lower limb isokinetic endurance in COPD: A comparison of angular velocities.

    Science.gov (United States)

    Ribeiro, Fernanda; Lépine, Pierre-Alexis; Garceau-Bolduc, Corine; Coats, Valérie; Allard, Étienne; Maltais, François; Saey, Didier

    2015-01-01

    The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD). After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV1) 55%±18% predicted) performed two quadriceps isokinetic endurance tests on two separate occasions within a 5-7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV1 for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated. High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities. Despite a limited sample size, our findings support the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work) at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index could also be assessed reliably at 90° per second. Evaluation of dyspnea and leg fatigue using the modified Borg scale of perceived exertion was poorly reliable and its clinical usefulness is questionable. These results should be useful in the design and interpretation of future interventions aimed at improving muscle endurance in COPD.

  8. On the constancy along cylinders of the angular velocity in the solar convection zone

    International Nuclear Information System (INIS)

    Durney, B.R.

    1976-01-01

    If, in the absence of rotation, the Sun's convection zone is adiabatic and if in the radial and latitudinal equations of motion the main balance of forces is between pressure gradients, Coriolis forces, and buoyancy forces (which is a good approximation if differential rotation is important over the entire convection zone and the large-scale velocities are not too large), then the perturbations in the convective flux and the pole-equator differences in flux (ΔF) are very large in the lower half of the convection zone, unless the angular velocity is constant along cylinders. The meridional velocities associated with this rotation law are not small, however, and could generate a significant ΔF. In this analysis compressibility was taken into account, but the latitudinal and radial dependence of the stabilizing effect of rotation on turbulent convection was neglected

  9. Isokinetic hamstring/quadriceps strength ratio: influence from joint angular velocity, gravity correction and contraction mode.

    Science.gov (United States)

    Aagaard, P; Simonsen, E B; Trolle, M; Bangsbo, J; Klausen, K

    1995-08-01

    This study investigated isokinetic peak- and angle-specific hamstring/quadriceps strength ratios (conventional H/Q ratio) obtained during concentric and eccentric muscle contraction and examined the influence of joint angular velocity and the effect of gravity correction on these ratios. Also, a 'functional' H/Q ratio was defined by calculating eccentric hamstring strength relative to concentric quadriceps strength (Hecc/Qcon' representative for knee extension) and calculating concentric hamstring strength relative to eccentric quadriceps strength (Hcon/Qecc' representative for knee flexion). The H/Q ratio was calculated based on isokinetic peak moment and 50 degree-moment (0 degree = full extension) obtained at joint angular velocities 30, 120 and 240 degrees s-1. Gravity corrected conventional H/Q ratio remained constant across speeds and contraction mode, ranging from 0.47 to 0.54 and from 0.49 to 0.56 based on peak and 50 degree moment, respectively. In contrast, non-corrected H/Q ratio increased during concentric contraction from 0.58 at 30 degrees s-1 to 0.74 at 240 degree s-1 (P ratio with variation in extension velocity. A potential 1:1 hamstring/quadriceps strength relationship was demonstrated for fast knee extension, indicating a significant functional capacity of the hamstring muscles for providing muscular stability at the knee joint in such situations.

  10. Interdependence of torque, joint angle, angular velocity and muscle action during human multi-joint leg extension.

    Science.gov (United States)

    Hahn, Daniel; Herzog, Walter; Schwirtz, Ansgar

    2014-08-01

    Force and torque production of human muscles depends upon their lengths and contraction velocity. However, these factors are widely assumed to be independent of each other and the few studies that dealt with interactions of torque, angle and angular velocity are based on isolated single-joint movements. Thus, the purpose of this study was to determine force/torque-angle and force/torque-angular velocity properties for multi-joint leg extensions. Human leg extension was investigated (n = 18) on a motor-driven leg press dynamometer while measuring external reaction forces at the feet. Extensor torque in the knee joint was calculated using inverse dynamics. Isometric contractions were performed at eight joint angle configurations of the lower limb corresponding to increments of 10° at the knee from 30 to 100° of knee flexion. Concentric and eccentric contractions were performed over the same range of motion at mean angular velocities of the knee from 30 to 240° s(-1). For contractions of increasing velocity, optimum knee angle shifted from 52 ± 7 to 64 ± 4° knee flexion. Furthermore, the curvature of the concentric force/torque-angular velocity relations varied with joint angles and maximum angular velocities increased from 866 ± 79 to 1,238 ± 132° s(-1) for 90-50° knee flexion. Normalised eccentric forces/torques ranged from 0.85 ± 0.12 to 1.32 ± 0.16 of their isometric reference, only showing significant increases above isometric and an effect of angular velocity for joint angles greater than optimum knee angle. The findings reveal that force/torque production during multi-joint leg extension depends on the combined effects of angle and angular velocity. This finding should be accounted for in modelling and optimisation of human movement.

  11. Influence of Tennis Racquet Kinematics on Ball Topspin Angular Velocity and Accuracy during the Forehand Groundstroke.

    Science.gov (United States)

    Kwon, Sunku; Pfister, Robin; Hager, Ronald L; Hunter, Iain; Seeley, Matthew K

    2017-12-01

    Forehand groundstroke effectiveness is important for tennis success. Ball topspin angular velocity (TAV) and accuracy are important for forehand groundstroke effectiveness, and have been extensively studied, previously; despite previous, quality studies, it was unclear whether certain racquet kinematics relate to ball TAV and shot accuracy during the forehand groundstroke. This study evaluated potential relationships between (1) ball TAV and (2) forehand accuracy, and five measures of racquet kinematics: racquet head impact angle (i.e., closed or open face), horizontal and vertical racquet head velocity before impact, racquet head trajectory (resultant velocity direction, relative to horizontal) before impact, and hitting zone length (quasi-linear displacement, immediately before and after impact). Thirteen collegiate-level tennis players hit forehand groundstrokes in a biomechanics laboratory, where racquet kinematics and ball TAV were measured, and on a tennis court, to assess accuracy. Correlational statistics were used to evaluate potential relationships between racquet kinematics, and ball TAV (mixed model) and forehand accuracy (between-subjects model; α = 0.05). We observed an average (1) racquet head impact angle, (2) racquet head trajectory before impact, relative to horizontal, (3) racquet head horizontal velocity before impact, (4) racquet head vertical velocity before impact, and (5) hitting zone length of 80.4 ± 3.6˚, 18.6 ± 4.3˚, 15.4 ± 1.4 m·s -1 , 6.6 ± 2.2 m·s -1 , and 79.8 ± 8.6 mm, respectively; and an average ball TAV of 969 ± 375 revolutions per minute. Only racquet head impact angle and racquet head vertical velocity, before impact, significantly correlated with ball TAV (p ball TAV is associated with a more closed racquet head impact angle (ranging from 70 to 85˚, relative to the ground) and increased racquet head vertical velocity before impact.

  12. Effect of angular velocity on soleus and medial gastrocnemius H-reflex during maximal concentric and eccentric muscle contraction.

    Science.gov (United States)

    Duclay, Julien; Robbe, Alice; Pousson, Michel; Martin, Alain

    2009-10-01

    At rest, the H-reflex is lower during lengthening than shortening actions. During passive lengthening, both soleus (SOL) and medial gastrocnemius (MG) H-reflex amplitudes decrease with increasing angular velocity. This study was designed to investigate whether H-reflex amplitude is affected by angular velocity during concentric and eccentric maximal voluntary contraction (MVC). Experiments were performed on nine healthy men. At a constant angular velocity of 60 degrees /s and 20 degrees /s, maximal H-reflex and M-wave potentials were evoked at rest (i.e., H(max) and M(max), respectively) and during concentric and eccentric MVC (i.e., H(sup) and M(sup), respectively). Regardless of the muscle, H(max)/M(max) was lower during lengthening than shortening actions and the H(sup)/M(sup) ratio was higher than H(max)/M(max) during lengthening actions. Whereas no action type and angular velocity effects on the MG H(sup)/M(sup) were found, the SOL H(sup)/M(sup) was lower during eccentric than concentric MVC and this depression was increased with higher angular velocity. Our findings indicate that the depression of the H-reflex amplitude during eccentric compared to concentric MVC depends mainly on the amount of inhibition induced by lengthening action. In conclusion, H-reflex should be evoked during both passive and active dynamic trials to evaluate the plasticity of the spinal loop.

  13. Neural correlates for angular head velocity in the rat dorsal tegmental nucleus

    Science.gov (United States)

    Bassett, J. P.; Taube, J. S.; Oman, C. M. (Principal Investigator)

    2001-01-01

    Many neurons in the rat lateral mammillary nuclei (LMN) fire selectively in relation to the animal's head direction (HD) in the horizontal plane independent of the rat's location or behavior. One hypothesis of how this representation is generated and updated is via subcortical projections from the dorsal tegmental nucleus (DTN). Here we report the type of activity in DTN neurons. The majority of cells (75%) fired as a function of the rat's angular head velocity (AHV). Cells exhibited one of two types of firing patterns: (1) symmetric, in which the firing rate was positively correlated with AHV during head turns in both directions, and (2) asymmetric, in which the firing rate was positively correlated with head turns in one direction and correlated either negatively or not at all in the opposite direction. In addition to modulation by AHV, some of the AHV cells (40.1%) were weakly modulated by the rat's linear velocity, and a smaller number were modulated by HD (11%) or head pitch (15.9%). Autocorrelation analyses indicated that with the head stationary, AHV cells displayed irregular discharge patterns. Because afferents from the DTN are the major source of information projecting to the LMN, these results suggest that AHV information from the DTN plays a significant role in generating the HD signal in LMN. A model is proposed showing how DTN AHV cells can generate and update the LMN HD cell signal.

  14. Knee Muscle Strength at Varying Angular Velocities and Associations with Gross Motor Function in Ambulatory Children with Cerebral Palsy

    Science.gov (United States)

    Hong, Wei-Hsien; Chen, Hseih-Ching; Shen, I-Hsuan; Chen, Chung-Yao; Chen, Chia-Ling; Chung, Chia-Ying

    2012-01-01

    The aim of this study was to evaluate the relationships of muscle strength at different angular velocities and gross motor functions in ambulatory children with cerebral palsy (CP). This study included 33 ambulatory children with spastic CP aged 6-15 years and 15 children with normal development. Children with CP were categorized into level I (n =…

  15. Estimating the angular velocity of a rigid body moving in the plane from tangential and centripetal acceleration measurements

    International Nuclear Information System (INIS)

    Cardou, Philippe; Angeles, Jorge

    2008-01-01

    Two methods are available for the estimation of the angular velocity of a rigid body from point-acceleration measurements: (i) the time-integration of the angular acceleration and (ii) the square-rooting of the centripetal acceleration. The inaccuracy of the first method is due mainly to the accumulation of the error on the angular acceleration throughout the time-integration process, which does not prevent that it be used successfully in crash tests with dummies, since these experiments never last more than one second. On the other hand, the error resulting from the second method is stable through time, but becomes inaccurate whenever the rigid body angular velocity approaches zero, which occurs in many applications. In order to take advantage of the complementarity of these two methods, a fusion of their estimates is proposed. To this end, the accelerometer measurements are modeled as exact signals contaminated with bias errors and Gaussian white noise. The relations between the variables at stake are written in the form of a nonlinear state-space system in which the angular velocity and the angular acceleration are state variables. Consequently, a minimum-variance-error estimate of the state vector is obtained by means of extended Kalman filtering. The performance of the proposed estimation method is assessed by means of simulation. Apparently, the resulting estimation method is more robust than the existing accelerometer-only methods and competitive with gyroscope measurements. Moreover, it allows the identification and the compensation of any bias error in the accelerometer measurements, which is a significant advantage over gyroscopes

  16. Influence of the tidal variations of the angular velocity on the rotation of the non-rigid Earth

    Science.gov (United States)

    Escapa, Alberto; Ferrándiz, José M.; Baenas, Tomás

    2017-04-01

    The lunisolar perturbation induces variations of the Earth's angular velocity components with nearly diurnal period, modulated by combinations of the orbital frequencies of the Moon and the Sun. These tidal variations of the angular velocity give rise to a redistribution of mass of the non-rigid Earth that, in turn, affects its rotational motion. We present a model of the former effect for a two-layer elastic Earth. Specifically, following the Hamiltonian formalism, we obtain formulae of this contribution for the precession and nutation of the Earth's figure axis. The analytical nature of our model allows its numerical evaluation for different Earth rheological models, providing values within current threshold requirements. For example, we obtain a value of the precession rate in longitude about 11 milliarcseconds per century, entailing a variation of the dynamical ellipticity of the Earth of two parts per million, comparable to other recent second order contributions to the precession rate (Baenas et al. 2017). Therefore, the effects of tidal variations of the angular velocity should be considered in the enhancement of the accuracy of the IAU2000 and IAU2006 nutation and precession theories.

  17. A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils

    OpenAIRE

    Li, Jian; Wu, Dan; Han, Yan

    2016-01-01

    Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent “I-shape” is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile ...

  18. Theoretical and Experimental Study of Radial Velocity Generation for Extending Bandwidth of Magnetohydrodynamic Angular Rate Sensor at Low Frequency

    Directory of Open Access Journals (Sweden)

    Yue Ji

    2015-12-01

    Full Text Available The magnetohydrodynamics angular rate sensor (MHD ARS has received much attention for its ultra-low noise in ultra-broad bandwidth and its impact resistance in harsh environments; however, its poor performance at low frequency hinders its work in long time duration. The paper presents a modified MHD ARS combining Coriolis with MHD effect to extend the measurement scope throughout the whole bandwidth, in which an appropriate radial flow velocity should be provided to satisfy simplified model of the modified MHD ARS. A method that can generate radial velocity by an MHD pump in MHD ARS is proposed. A device is designed to study the radial flow velocity generated by the MHD pump. The influence of structure and physical parameters are studied by numerical simulation and experiment of the device. The analytic expression of the velocity generated by the energized current drawn from simulation and experiment are consistent, which demonstrates the effectiveness of the method generating radial velocity. The study can be applied to generate and control radial velocity in modified MHD ARS, which is essential for the two effects combination throughout the whole bandwidth.

  19. Identification of Plate Blocks Based on a Cluster Analysis of GNSS Data in the Angular Velocity Space

    Science.gov (United States)

    Takahashi, A.; Okazaki, T.; Takeuchi, K.; Iwata, T.; Fukahata, Y.

    2016-12-01

    The motion of a rigid plate on a sphere is expressed as rotation around an axis. Recently, statistical approaches were proposed to identify boundaries of crustal blocks from observed GNSS data. Simpson et al. (2012) showed the advantage of clustering algorithm to distinguish block boundaries. Savage and Simpson (2013) extended the study by adding an iterative algorithm to take account of the effects of a sphere. These studies successfully showed a way to identify block structures in the West Coast of the U.S.However, it is still difficult to apply the methods to global GNSS data so as to identify plate blocks. So, we developed a method to tackle this problem. First, we formulated the relationship among the geographical location of the GNSS station, observed velocity at the GNSS station, and candidates of the Euler pole. The relationship shows that the candidates of the Euler pole are expressed as a straight line in the angular velocity space, because the cross product of an Euler pole vector and a position vector of a GNSS station should be an observed velocity vector. We can expect that lines that correspond to GNSS data crosses at a point in the angular velocity space as long as these data belong to the same crustal block. We used an octree algorithm and graph clustering algorithm to spot crossing points. Each cross point represents a cluster, namely a crustal block.In order to assess the validity of our method, we applied it to GNSS data in the West Coast of U.S. where, four segments were identified in Simpson et al. (2012), and we obtained the same result as them. We confirmed that our new formulation reduces to the existing formulation in the velocity space when the scale of a clustering region is much smaller than the entire Earth.For application to global scale, we performed a numerical experiment. We deployed 360 observation stations on the earth mostly uniformly and calculated velocities at stations from six imaginary Euler poles. We translated calculated

  20. Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance.

    Science.gov (United States)

    Lee, Chan-Bok; Eun, Denny; Kim, Kang-Ho; Park, Jae-Wan; Jee, Yong-Seok

    2017-04-01

    Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints.

  1. Smearing model and restoration of star image under conditions of variable angular velocity and long exposure time.

    Science.gov (United States)

    Sun, Ting; Xing, Fei; You, Zheng; Wang, Xiaochu; Li, Bin

    2014-03-10

    The star tracker is one of the most promising attitude measurement devices widely used in spacecraft for its high accuracy. High dynamic performance is becoming its major restriction, and requires immediate focus and promotion. A star image restoration approach based on the motion degradation model of variable angular velocity is proposed in this paper. This method can overcome the problem of energy dispersion and signal to noise ratio (SNR) decrease resulting from the smearing of the star spot, thus preventing failed extraction and decreased star centroid accuracy. Simulations and laboratory experiments are conducted to verify the proposed methods. The restoration results demonstrate that the described method can recover the star spot from a long motion trail to the shape of Gaussian distribution under the conditions of variable angular velocity and long exposure time. The energy of the star spot can be concentrated to ensure high SNR and high position accuracy. These features are crucial to the subsequent star extraction and the whole performance of the star tracker.

  2. Measurements on multichannel arrays. The angular dependence of the absolute intensity and the velocity distribution

    International Nuclear Information System (INIS)

    Beijerinck, H.C.W.; Verster, N.F.

    1974-01-01

    Three multichannel arrays with channel-diameters of 16, 50 and 140μm have been investigated using O 2 with flow rates of 4 10 -5 through 8 10 -3 torr l s -1 mm -2 . All experimental values of the peaking factor K are described by one experimental curve if the peaking factor is reduced by K*=KT, where T is the Clausing factor, and then is plotted vs. the reduced entrance density eta*=L/lambda, where lambda is the mean free path corresponding to the entrance density and L is the length of the channel. At eta*=1 the experimental curve lies 40% below Giordmaine and Wang theory, and this deviation increases slightly with increasing eta*. In the plot of the reduced half-width-half-maximum THETAsub(1/2)sup(*)=THETAsub(1/2)T -1 vs. eta* all data are also well represented by a single experimental curve. The center-line velocity distribution is described in terms of a deformation function GAMMA(v), to be applied to the Maxwell-Boltzmann velocity distribution from an ideal orifice

  3. Angular and velocity analysis of the three-fold events in the Xe+Cu reaction at 45 MeV/u

    International Nuclear Information System (INIS)

    Bruno, M.; D'Agostino, M.; Fiandri, M.L.; Fuschini, E.; Manduci, L.; Mastinu, P.F.; Milazzo, P.M.; Gramegna, F.; Ferrero, A.M.J.; Gulminelli, F.; Iori, I.; Moroni, A.; Scardaoni, R.; Buttazzo, P.; Margagliotti, G.V.; Vannini, G.; Auger, G.; Plagnol, E.

    1994-01-01

    An analysis of the angular and velocity distributions of the intermediate mass fragments produced in the reaction Xe+Cu at 45 MeV/u is presented. Events coming from central collisions are selected and compared with predictions of different models based on a statistical deexcitation of an equilibrated source. The angular and velocity correlations show that the experimental production of three nearly-equal mass fragments cannot be explained by a sequential binary decay and is compatible with a multifragmentation mechanism. ((orig.))

  4. Determining whether a ball will land behind or in front of you: not just a combination of expansion and angular velocity.

    Science.gov (United States)

    Brouwer, Anne-Marie; López-Moliner, Joan; Brenner, Eli; Smeets, Jeroen B J

    2006-02-01

    We propose and evaluate a source of information that ball catchers may use to determine whether a ball will land behind or in front of them. It combines estimates for the ball's horizontal and vertical speed. These estimates are based, respectively, on the rate of angular expansion and vertical velocity. Our variable could account for ball catchers' data of Oudejans et al. [The effects of baseball experience on movement initiation in catching fly balls. Journal of Sports Sciences, 15, 587-595], but those data could also be explained by the use of angular expansion alone. We therefore conducted additional experiments in which we asked subjects where simulated balls would land under conditions in which both angular expansion and vertical velocity must be combined for obtaining a correct response. Subjects made systematic errors. We found evidence for the use of angular velocity but hardly any indication for the use of angular expansion. Thus, if catchers use a strategy that involves combining vertical and horizontal estimates of the ball's speed, they do not obtain their estimates of the horizontal component from the rate of expansion alone.

  5. Resistance training performed at distinct angular velocities elicits velocity-specific alterations in muscle strength and mobility status in older adults.

    Science.gov (United States)

    Englund, Davis A; Sharp, Rick L; Selsby, Joshua T; Ganesan, Shanthi S; Franke, Warren D

    2017-05-01

    The purpose of this study was to compare the effects of high and low velocity knee extension training on changes in muscle strength and mobility status in high-functioning older adults. Twenty-six (16 female, 10 male) older adults (mean age of 65) were randomized to either 6weeks of low velocity resistance training (LVRT) performed at 75°/s or high velocity resistance training (HVRT) performed at 240°/s. Both groups performed 3 sets of knee extension exercises at maximal effort, 3 times a week. Muscle strength was assessed through a range of testing velocities on an isokinetic dynamometer. Mobility status was assessed with the short physical performance battery (SPPB) and myosin heavy chain (MyHC) transcript levels were quantified via qRT-PCR. From baseline to post-training, there were several significant (Pstrength and functional characteristics in LVRT (n=13) and HVRT (n=13) groups. From baseline to post-training, MyHC-α mRNA and MyHC-IIa mRNA showed a significant (Ptraining stimulus for the older adult. The present study demonstrates, in addition to increased strength and functional outcomes, HVRT elicits a potentially therapeutic (i.e., slow to fast) transcriptional response in MyHC. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Azimuthal velocity profiles in Rayleigh-stable Taylor–Couette flow and implied axial angular momentum transport

    NARCIS (Netherlands)

    Nordsiek, F.; Huisman, Sander Gerard; van der Veen, Roeland; Sun, Chao; Lohse, Detlef; Lathrop, D.P.

    2015-01-01

    We present azimuthal velocity profiles measured in a Taylor–Couette apparatus, which has been used as a model of stellar and planetary accretion disks. The apparatus has a cylinder radius ratio of ${\\it\\eta}=0.716$η=0.716, an aspect ratio of ${\\it\\Gamma}=11.74$Γ=11.74, and the plates closing the

  7. Anisotropy of the Elastic Properties of Normal and Pathological Myocardium: Angular Dependence of Ultrasonic Backscatter, Attenuation, and Velocity.

    Science.gov (United States)

    Verdonk, Edward Dennis

    The focus of this thesis is the measurement of anisotropies in the ultrasonic parameters of soft tissues. The goal is to contribute to a better understanding of the physics which underlies the interaction of ultrasonic waves with inhomogeneous and anisotropic media. Broadband measurements using a piezoelectric transducer are reported for investigations of excised specimens of human and canine myocardial tissue. Emphasis is placed on identifying the effect that the muscle fiber orientation, relative to the direction of insonification, has on the propagation and scattering properties of ultrasonic waves. Results of the anisotropy of backscatter, the anisotropy of attenuation, and the anisotropy of quasilongitudinal velocity are presented for data obtained in 2^ circ increments through the full 360 ^circ relative to the myofibers. Measured velocities are used in conjunction with measured specimen densities to determine the elastic stiffness constants c_{11} and c_ {33} and to estimate specific mechanical moduli for thin layers of myocardium.

  8. Characterizing the Velocity Profile of a Swirling Gas Experiment by Particle Imaging Velocimetry to Study Angular Momentum Transport in Accretion Disks

    Science.gov (United States)

    Greess, Samuel; Ji, Hantao; Merino, Enrique; Berrios, William

    2013-10-01

    The method by which angular momentum transfers between different sections of accretion disks is a matter of ongoing debate. One suggested answer is Magnetorotational instability (MRI), which would facilitate this transfer through the magnetic interactions between particles at different distances from the center of the disk. While ongoing experiments with MRI have focused on the use of liquid metals to test the effects of magnetic fields, we are developing a swirling gas experiment to study effects beyond incompressible hydrodynamics, including compressible gas dynamics and plasma effects when gas is ionized. A second-generation prototype swirling gas experiment has been built to test the principle and to establish favorable rotation profiles using a chamber of swirling fog to simulate the formation and movement of accretion disks about some gravitational center. The paths of the visible fog particles can then be analyzed with Particle Imaging Velocimetry (PIV) techniques; these velocity measurements can then be organized by a Python program. Anticipated results include a radial profile of velocities at different times during the gas injection process, as well as further refinement of the fog chamber design to improve the accuracy in controlling the profile.

  9. Velocity-tunable slow beams of cold O2 in a single spin-rovibronic state with full angular-momentum orientation by multistage Zeeman deceleration

    Science.gov (United States)

    Wiederkehr, A. W.; Schmutz, H.; Motsch, M.; Merkt, F.

    2012-08-01

    Cold samples of oxygen molecules in supersonic beams have been decelerated from initial velocities of 390 and 450 m s-1 to final velocities in the range between 150 and 280 m s-1 using a 90-stage Zeeman decelerator. (2 + 1) resonance-enhanced-multiphoton-ionization (REMPI) spectra of the 3sσ g 3Π g (C) ? two-photon transition of O2 have been recorded to characterize the state selectivity of the deceleration process. The decelerated molecular sample was found to consist exclusively of molecules in the J ‧‧ = 2 spin-rotational component of the X ? ground state of O2. Measurements of the REMPI spectra using linearly polarized laser radiation with polarization vector parallel to the decelerator axis, and thus to the magnetic-field vector of the deceleration solenoids, further showed that only the ? magnetic sublevel of the N‧‧ = 1, J ‧‧ = 2 spin-rotational level is populated in the decelerated sample, which therefore is characterized by a fully oriented total-angular-momentum vector. By maintaining a weak quantization magnetic field beyond the decelerator, the polarization of the sample could be maintained over the 5 cm distance separating the last deceleration solenoid and the detection region.

  10. Angular correlation methods

    International Nuclear Information System (INIS)

    Ferguson, A.J.

    1974-01-01

    An outline of the theory of angular correlations is presented, and the difference between the modern density matrix method and the traditional wave function method is stressed. Comments are offered on particular angular correlation theoretical techniques. A brief discussion is given of recent studies of gamma ray angular correlations of reaction products recoiling with high velocity into vacuum. Two methods for optimization to obtain the most accurate expansion coefficients of the correlation are discussed. (1 figure, 53 references) (U.S.)

  11. Determining whether a ball will land behind or in front of you: Not just a combination of expansion and angular velocity

    NARCIS (Netherlands)

    Brouwer, A.M.; Lopez-Moliner, J.; Brenner, E.; Smeets, J.B.J.

    2006-01-01

    We propose and evaluate a source of information that ball catchers may use to determine whether a ball will land behind or in front of them. It combines estimates for the ball's horizontal and vertical speed. These estimates are based, respectively, on the rate of angular expansion and vertical

  12. Estimating the accuracy of the technique of reconstructing the rotational motion of a satellite based on the measurements of its angular velocity and the magnetic field of the Earth

    Science.gov (United States)

    Belyaev, M. Yu.; Volkov, O. N.; Monakhov, M. I.; Sazonov, V. V.

    2017-09-01

    The paper has studied the accuracy of the technique that allows the rotational motion of the Earth artificial satellites (AES) to be reconstructed based on the data of onboard measurements of angular velocity vectors and the strength of the Earth magnetic field (EMF). The technique is based on kinematic equations of the rotational motion of a rigid body. Both types of measurement data collected over some time interval have been processed jointly. The angular velocity measurements have been approximated using convenient formulas, which are substituted into the kinematic differential equations for the quaternion that specifies the transition from the body-fixed coordinate system of a satellite to the inertial coordinate system. Thus obtained equations represent a kinematic model of the rotational motion of a satellite. The solution of these equations, which approximate real motion, has been found by the least-square method from the condition of best fitting between the data of measurements of the EMF strength vector and its calculated values. The accuracy of the technique has been estimated by processing the data obtained from the board of the service module of the International Space Station ( ISS). The reconstruction of station motion using the aforementioned technique has been compared with the telemetry data on the actual motion of the station. The technique has allowed us to reconstruct the station motion in the orbital orientation mode with a maximum error less than 0.6° and the turns with a maximal error of less than 1.2°.

  13. Angular Momentum

    Science.gov (United States)

    Shakur, Asif; Sinatra, Taylor

    2013-01-01

    The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in…

  14. Nuclear rotation at high angular velocities

    International Nuclear Information System (INIS)

    Johnson, A.

    1975-01-01

    A short review is given of the available experimental information as well as a discussion of some freatures of the experimental procedures. For relevant theories of nuclear rotation the reader is referred to other papers in these Proceedings. (author)

  15. A kinematic model for calculating the magnitude of angular ...

    African Journals Online (AJOL)

    Keplerian velocity laws imply the existence of velocity shear and shear viscosity within an accretion disk. Due to this viscosity, angular momentum is transferred from the faster moving inner regions to the slower-moving outer regions of the disk. Here we have formulated a model for calculating the magnitude of angular ...

  16. Angular Accelerating White Light

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2015-08-01

    Full Text Available angular acceleration during propagation which is achieved by superpositions of Bessel beams with non-canonical phase functions. They demonstrate these angular accelerating fields by modulating the phase and amplitude of a supercontinuum source with the use...

  17. Professional AngularJS

    CERN Document Server

    Karpov, Valeri

    2015-01-01

    A comprehensive guide to AngularJS, Google's open-source client-side framework for app development. Most of the existing guides to AngularJS struggle to provide simple and understandable explanations for more advanced concepts. As a result, some developers who understand all the basic concepts of AngularJS struggle when it comes to building more complex real-world applications. Professional AngularJS provides a thorough understanding of AngularJS, covering everything from basic concepts, such as directives and data binding, to more advanced concepts like transclusion, build systems, and auto

  18. Spin Rate of a Racquetball Due To Angular Impact

    Directory of Open Access Journals (Sweden)

    Dolev Illouz

    2014-12-01

    Full Text Available The relationship between the impact angle of a racquetball and the resulting angular velocity of the ball was investigated. Impact angles ranging from 0° to 80° were tested. The ball was dropped at constant speed on a plywood board that could be angled and the impact was filmed at 600 fps. The video was then analyzed to determine the angular velocity of the ball after the bounce. It was found that there is a proportional relationship between the incoming impact angle (θ and angular velocity (ω of the racquetball, for angles up to 50°, indicating that the ball did not slip during impact at these angles.

  19. Angular Acceleration without Torque?

    Science.gov (United States)

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

  20. Rotations and angular momentum

    International Nuclear Information System (INIS)

    Nyborg, P.; Froyland, J.

    1979-01-01

    This paper is devoted to the analysis of rotational invariance and the properties of angular momentum in quantum mechanics. In particular, the problem of addition of angular momenta is treated in detail, and tables of Clebsch-Gordan coefficients are included

  1. Quark Orbital Angular Momentum

    Directory of Open Access Journals (Sweden)

    Burkardt Matthias

    2015-01-01

    Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.

  2. Optical Angular Momentum

    International Nuclear Information System (INIS)

    Arimondo, Ennio

    2004-01-01

    For many years the Institute of Physics has published books on hot topics based on a collection of reprints from different journals, including some remarks by the editors of each volume. The book on Optical Angular Momentum, edited by L Allen, S M Barnett and M J Padgett, is a recent addition to the series. It reproduces forty four papers originally published in different journals and in a few cases it provides direct access to works not easily accessible to a web navigator. The collection covers nearly a hundred years of progress in physics, starting from an historic 1909 paper by Poynting, and ending with a 2002 paper by Padgett, Barnett and coworkers on the measurement of the orbital angular momentum of a single photon. The field of optical angular momentum has expanded greatly, creating an interdisciplinary attraction for researchers operating in quantum optics, atomic physics, solid state physics, biophysics and quantum information theory. The development of laser optics, especially the control of single mode sources, has made possible the specific design of optical radiation modes with a high degree of control on the light angular momentum. The editors of this book are important figures in the field of angular momentum, having contributed to key progress in the area. L Allen published an historical paper in 1999, he and M J Padgett (together with M Babiker) produced few years ago a long review article which is today still the most complete basic introduction to the angular momentum of light, while S M Barnett has contributed several high quality papers to the progress of this area of physics. The editors' choice provides an excellent overview to all readers, with papers classified into eight different topics, covering the basic principles of the light and spin and orbital angular momentum, the laboratory tools for creating laser beams carrying orbital angular momentum, the optical forces and torques created by laser beams carrying angular momentum on

  3. Fission fragment angular momentum

    International Nuclear Information System (INIS)

    Frenne, D. De

    1991-01-01

    Most of the energy released in fission is converted into translational kinetic energy of the fragments. The remaining excitation energy will be distributed among neutrons and gammas. An important parameter characterizing the scission configuration is the primary angular momentum of the nascent fragments. Neutron emission is not expected to decrease the spin of the fragments by more than one unit of angular momentum and is as such of less importance in the determination of the initial fragment spins. Gamma emission is a suitable tool in studying initial fragment spins because the emission time, number, energy, and multipolarity of the gammas strongly depend on the value of the primary angular momentum. The main conclusions of experiments on gamma emission were that the initial angular momentum of the fragments is large compared to the ground state spin and oriented perpendicular to the fission axis. Most of the recent information concerning initial fragment spin distributions comes from the measurement of isomeric ratios for isomeric pairs produced in fission. Although in nearly every mass chain isomers are known, only a small number are suitable for initial fission fragment spin studies. Yield and half-life considerations strongly limit the number of candidates. This has the advantage that the behavior of a specific isomeric pair can be investigated for a number of fissioning systems at different excitation energies of the fragments and fissioning nuclei. Because most of the recent information on primary angular momenta comes from measurements of isomeric ratios, the global deexcitation process of the fragments and the calculation of the initial fragment spin distribution from measured isomeric ratios are discussed here. The most important results on primary angular momentum determinations are reviewed and some theoretical approaches are given. 45 refs., 7 figs., 2 tabs

  4. Angular momentum projected semiclassics

    International Nuclear Information System (INIS)

    Hasse, R.W.

    1986-10-01

    By using angular momentum projected plane waves as wave functions, we derive semiclassical expressions for the single-particle propagator, the partition function, the nonlocal density matrix, the single-particle density and the one particle- one hole level density for fixed angular momentum and fixed z-component or summed over the z-components. Other quantities can be deduced from the propagator. In coordinate space (r, r') the relevant quantities depend on vertical stroker - r 3 vertical stroke instead of vertical stroker - r'vertical stroke and in Wigner space (R, P) they become proportional to the angular momentum constraints δ(vertical strokeRxPvertical stroke/ℎ - l) and δ((RxP) z /ℎ - m). As applications we calculate the single-particle and one particle- one hole level densities for harmonic oscillator and Hill-Wheeler box potentials and the imaginary part of the optical potential and its volume integral with an underlying harmonic oscillator potential and a zero range two-body interaction. (orig.)

  5. Angular Momentum in Fission

    Science.gov (United States)

    Gönnenwein, F.; Bunakov, V.; Dorvaux, O.; Gagarski, A.; Guseva, I.; Hanappe, F.; Kadmensky, S.; von Kalben, J.; Khlebnikov, S.; Kinnard, V.; Kopatch, Yu.; Mutterer, M.; Nesvizhevsky, V.; Petrov, G.; Prokhorova, E.; Rubchenya, V.; Sillanpää, M.; Simpson, G.; Sokolov, V.; Soldner, T.; Stuttgé, L.; Tiourine, G.; Trzaska, W.; Tsekhanovich, I.; Wagemans, C.; Wollersheim, H.-J.; Zavarukhina, T.; Zimmer, O.

    2008-04-01

    Three novel experiments in spontaneous and thermal neutron induced fission all with a bearing on angular momentum in fission are reviewed. In the first experiment it was observed that, in the reaction 235U(n, f) with incident polarized cold neutrons, the nucleus undergoing scission is rotating. This was inferred from the shift in angular distributions of ternary particles being dependent on the orientation of neutron spin. In the second study the properties of the angular momentum of spherical fission fragments was investigated. Current theories trace the spin of fragments to their deformations allowing for collective rotational vibrations at scission. However, in particular the spherical 132Te isotope exhibits a large spin at variance with theory. Exploiting the specific properties of cold deformed fission it could be proven that, for 132Te, single particle excitations instead of collective modes are responsible for the large spin observed. In a third project a pilot study was exploring the possibility to search for an evaporation of neutrons from fragments being anisotropic in their own cm-system. Due to fragment spin this anisotropy is claimed since decades to exist. It was so far never observed. A scheme has been devised and tested were triple coincidences between a fragment and two neutrons are evaluated in a way to bring the cm-anisotropy into the foreground while getting rid of the kinematical anisotropy in the lab-system due to evaporation from moving fragments. The test was run for spontaneous fission of 252Cf.

  6. On the angular momentum in star formation

    International Nuclear Information System (INIS)

    Horedt, G.P.

    1978-01-01

    The author discusses the rotation of interstellar clouds which are in a stage immediately before star formation. Cloud collisions seem to be the principal cause of the observed rotation of interstellar clouds. The rotational motion of the clouds is strongly influenced by turbulence. Theories dealing with the resolution of the angular momentum problem in star formation are classified into five major groups. The old idea that the angular momentum of an interstellar cloud passes during star formation into the angular momentum of double star systems and/or circumstellar clouds, is developed. It is suggested that a rotating gas cloud contracts into a ring-like structure which fragments into self-gravitating subcondensations. By collisions and gas accretion these subcondensations accrete into binary systems surrounded by circumstellar clouds. Using some rough approximations the authors find analytical expressions for the semi-major axis of the binary system and for the density of the circumstellar clouds as a function of the initial density and of the initial angular velocity of an interstellar cloud. The obtained values are well within the observational limits. (Auth.)

  7. Linear and angular control of circular walking in healthy older adults and subjects with cerebellar ataxia.

    Science.gov (United States)

    Goodworth, Adam D; Paquette, Caroline; Jones, Geoffrey Melvill; Block, Edward W; Fletcher, William A; Hu, Bin; Horak, Fay B

    2012-05-01

    Linear and angular control of trunk and leg motion during curvilinear navigation was investigated in subjects with cerebellar ataxia and age-matched control subjects. Subjects walked with eyes open around a 1.2-m circle. The relationship of linear to angular motion was quantified by determining the ratios of trunk linear velocity to trunk angular velocity and foot linear position to foot angular position. Errors in walking radius (the ratio of linear to angular motion) also were quantified continuously during the circular walk. Relative variability of linear and angular measures was compared using coefficients of variation (CoV). Patterns of variability were compared using power spectral analysis for the trunk and auto-covariance analysis for the feet. Errors in radius were significantly increased in patients with cerebellar damage as compared to controls. Cerebellar subjects had significantly larger CoV of feet and trunk in angular, but not linear, motion. Control subjects also showed larger CoV in angular compared to linear motion of the feet and trunk. Angular and linear components of stepping differed in that angular, but not linear, foot placement had a negative correlation from one stride to the next. Thus, walking in a circle was associated with more, and a different type of, variability in angular compared to linear motion. Results are consistent with increased difficulty of, and role of the cerebellum in, control of angular trunk and foot motion for curvilinear locomotion.

  8. Optical angular momentum and atoms.

    Science.gov (United States)

    Franke-Arnold, Sonja

    2017-02-28

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

  9. AngularJS directives

    CERN Document Server

    Vanston, Alex

    2013-01-01

    This book uses a practical, step-by-step approach, starting with how to build directives from the ground up before moving on to creating web applications comprised of multiple modules all working together to provide the best user experience possible.This book is intended for intermediate JavaScript developers who are looking to enhance their understanding of single-page web application development with a focus on AngularJS and the JavaScript MVC frameworks.It is expected that readers will understand basic JavaScript patterns and idioms and can recognize JSON formatted data.

  10. Angular Distribution of GRBs

    Directory of Open Access Journals (Sweden)

    L. G. Balázs

    2012-01-01

    Full Text Available We studied the complete randomness of the angular distribution of BATSE gamma-ray bursts (GRBs. Based on their durations and peak fluxes, we divided the BATSE sample into 5 subsamples (short1, short2, intermediate, long1, long2 and studied the angular distributions separately. We used three methods to search for non-randomness in the subsamples: Voronoi tesselation, minimal spanning tree, and multifractal spectra. To study any non-randomness in the subsamples we defined 13 test-variables (9 from Voronoi tesselation, 3 from the minimal spanning tree and one from the multifractal spectrum. We made Monte Carlo simulations taking into account the BATSE’s sky-exposure function. We tested therandomness by introducing squared Euclidean distances in the parameter space of the test-variables. We recognized that the short1, short2 groups deviate significantly (99.90%, 99.98% from the fully random case in the distribution of the squared Euclidean distances but this is not true for the long samples. In the intermediate group, the squared Euclidean distances also give significant deviation (98.51%.

  11. Gravitational Field of Ultrarelativistic Objects with Angular Momentum

    International Nuclear Information System (INIS)

    Fursaev, Dmitri V

    2006-01-01

    A brief review of recently found gyraton metrics which describe the gravitational field of objects having an angular momentum and moving with the velocity of light is given. The gyraton metrics belong to a class of exact plane wave solutions of four and higher dimensional Einstein equations in vacuum or in the presence of a negative cosmological constant

  12. Demonstrating the Conservation of Angular Momentum Using Model Cars Moving along a Rotating Rod

    Science.gov (United States)

    Abdul-Razzaq, Wathiq; Golubovic, Leonardo

    2013-01-01

    We have developed an exciting non-traditional experiment for our introductory physics laboratories to help students to understand the principle of conservation of angular momentum. We used electric toy cars moving along a long rotating rod. As the cars move towards the centre of the rod, the angular velocity of this system increases.…

  13. WESTERBORK OBSERVATIONS OF HIGH-VELOCITY CLOUDS - THE DATA

    NARCIS (Netherlands)

    WAKKER, BP

    1991-01-01

    The results of Westerbork * observations of small-scale structure in high-velocity clouds (HVCs) at 1' angular and 1 km s-1 velocity resolution are presented in the form of a table of observational parameters, maps of hydrogen column density, velocity-right ascension cuts, and histograms of the

  14. Angular integrals in d dimensions

    International Nuclear Information System (INIS)

    Somogyi, Gabor

    2011-01-01

    We discuss the evaluation of certain d dimensional angular integrals which arise in perturbative field theory calculations. We find that the angular integral with n denominators can be computed in terms of a certain special function, the so-called H-function of several variables. We also present several illustrative examples of the general result and briefly consider some applications. (orig.)

  15. Angular-domain scattering interferometry.

    Science.gov (United States)

    Shipp, Dustin W; Qian, Ruobing; Berger, Andrew J

    2013-11-15

    We present an angular-scattering optical method that is capable of measuring the mean size of scatterers in static ensembles within a field of view less than 20 μm in diameter. Using interferometry, the method overcomes the inability of intensity-based models to tolerate the large speckle grains associated with such small illumination areas. By first estimating each scatterer's location, the method can model between-scatterer interference as well as traditional single-particle Mie scattering. Direct angular-domain measurements provide finer angular resolution than digitally transformed image-plane recordings. This increases sensitivity to size-dependent scattering features, enabling more robust size estimates. The sensitivity of these angular-scattering measurements to various sizes of polystyrene beads is demonstrated. Interferometry also allows recovery of the full complex scattered field, including a size-dependent phase profile in the angular-scattering pattern.

  16. AngularJS testing cookbook

    CERN Document Server

    Bailey, Simon

    2015-01-01

    This book is intended for developers who have an understanding of the basic principles behind both AngularJS and test-driven development. You, as a developer, are interested in eliminating the fear related to either introducing tests to an existing codebase or starting out testing on a fresh AngularJS application. If you're a team leader or part of a QA team with the responsibility of ensuring full test coverage of an application, then this book is ideal for you to comprehend the full testing scope required by your developers. Whether you're new to or are well versed with AngularJS, this book

  17. Orbital velocity

    OpenAIRE

    Modestino, Giuseppina

    2016-01-01

    The trajectory and the orbital velocity are determined for an object moving in a gravitational system, in terms of fundamental and independent variables. In particular, considering a path on equipotential line, the elliptical orbit is naturally traced, verifying evidently the keplerian laws. The case of the planets of the solar system is presented.

  18. Lidar Orbital Angular Momentum Sensor

    Data.gov (United States)

    National Aeronautics and Space Administration — The recognition in recent decades that electromagnetic fields have angular momentum (AM) in the form of not only polarization (or spin AM) but also orbital (OAM) has...

  19. Angular momentum from tidal torques

    International Nuclear Information System (INIS)

    Barnes, J.; Efstathiou, G.; Cambridge Univ., England)

    1987-01-01

    The origin of the angular momentum of bound objects in large N-body simulations is studied using three sets of models. One model with white-noise initial conditions is analyzed as well as two in which the initial conditions have more power on large scales, as predicted in models with cold dark matter. The growth and distribution of angular momentum in individual objects is studied and it is found that the specific angular momentum distribution of bound clumps increases in a near linear fashion with radius while the orientation of the angular momentum in the inner high-density regions is often poorly correlated with that of the outer parts. It is also found that the dimensionless spin parameter is insensitive to the initial perturbation spectrum and has a median value of about 0.05. 61 references

  20. Plasmons with orbital angular momentum

    International Nuclear Information System (INIS)

    Mendonca, J. T.; Ali, S.; Thide, B.

    2009-01-01

    Electron plasma waves carrying orbital angular momentum are investigated in an unmagnetized collisionless plasma composed of inertial electrons and static ions. For this purpose, the usual plasmon dispersion relation is employed to derive an approximate paraxial equation. The latter is analyzed with a Gaussian beam solution. For a finite angular momentum associated with the plasmon, Laguerre-Gaussian (LG) solutions are employed for solving the electrostatic potential problem which gives approximate solution and is valid for plasmon beams in the paraxial approximation. The LG potential determines the electric field components and energy flux of plasmons with finite angular momentum. Numerical illustrations show that the radial and angular mode numbers strongly modify the profiles of the LG potential.

  1. Rectilinear Graphs and Angular Resolution

    NARCIS (Netherlands)

    Bodlaender, H.L.; Tel, G.

    2003-01-01

    In this note we show that a planar graph with angular resolution at least π/2 can be drawn with all angles an integer multiple of π/2, that is, in a rectilinear manner. Moreover, we show that for d ≠ 4, d › 2, having an angular resolution of 2π/d does not imply that the graph can be drawn with all

  2. Angular Momentum Transport in Turbulent Flow between Independently Rotating Cylinders

    International Nuclear Information System (INIS)

    Paoletti, M. S.; Lathrop, D. P.

    2011-01-01

    We present measurements of the angular momentum flux (torque) in Taylor-Couette flow of water between independently rotating cylinders for all regions of the (Ω 1 , Ω 2 ) parameter space at high Reynolds numbers, where Ω 1 (Ω 2 ) is the inner (outer) cylinder angular velocity. We find that the Rossby number Ro=(Ω 1 -Ω 2 )/Ω 2 fully determines the state and torque G as compared to G(Ro=∞)≡G ∞ . The ratio G/G ∞ is a linear function of Ro -1 in four sections of the parameter space. For flows with radially increasing angular momentum, our measured torques greatly exceed those of previous experiments [Ji et al., Nature (London), 444, 343 (2006)], but agree with the analysis of Richard and Zahn [Astron. Astrophys. 347, 734 (1999)].

  3. Uncertainty principle for angular position and angular momentum

    International Nuclear Information System (INIS)

    Franke-Arnold, Sonja; Barnett, Stephen M; Yao, Eric; Leach, Jonathan; Courtial, Johannes; Padgett, Miles

    2004-01-01

    The uncertainty principle places fundamental limits on the accuracy with which we are able to measure the values of different physical quantities (Heisenberg 1949 The Physical Principles of the Quantum Theory (New York: Dover); Robertson 1929 Phys. Rev. 34 127). This has profound effects not only on the microscopic but also on the macroscopic level of physical systems. The most familiar form of the uncertainty principle relates the uncertainties in position and linear momentum. Other manifestations include those relating uncertainty in energy to uncertainty in time duration, phase of an electromagnetic field to photon number and angular position to angular momentum (Vaccaro and Pegg 1990 J. Mod. Opt. 37 17; Barnett and Pegg 1990 Phys. Rev. A 41 3427). In this paper, we report the first observation of the last of these uncertainty relations and derive the associated states that satisfy the equality in the uncertainty relation. We confirm the form of these states by detailed measurement of the angular momentum of a light beam after passage through an appropriate angular aperture. The angular uncertainty principle applies to all physical systems and is particularly important for systems with cylindrical symmetry

  4. Electromagnetic angular positioner based on DC micromotor

    Directory of Open Access Journals (Sweden)

    Bodnicki Maciej

    2018-01-01

    Full Text Available The presented works concerned launching of an angular positioner powered by an electromagnetic actuator, designed for performing angular micromovements within a range of few microradians. The principle of operation is based on balancing the electromagnetic torque of the motor with a torque that is twisting a compliant element. As electrodynamic actuators have no distinguished controlled positions, therefore in typical positioning systems desired positions are obtained applying a closed-loop position control. Usually, such systems employ also a feedback (dumping related to velocity of the moving elements, what simplifies forming of dynamics of the system. The design of the physical model employs a DC micromotor, whose rotor is coupled with a torsional torquemeter. A feedback signal is generated by resistive strain gauges. The paper presents a mathematical model of the positioning system, results of simulation study as well as results of experimental study. The simulation study indicates that it is possible to select such design features and such type of the micoromotor that a high dynamics of positioning is ensured.

  5. Instant AngularJS starter

    CERN Document Server

    Menard, Dan

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. This book is written in an easytoread style, with a strong emphasis on realworld, practical examples. Stepbystep explanations are provided for performing important tasks.This book is for web developers familiar with JavascriptIt doesn't cover the history of AngularJS, and it's not a pitch to convince you that AngularJS is the best framework on the entire web. It's a guide to help you learn everything you need to know about AngularJS in as few pa

  6. Automated Angular Momentum Recoupling Algebra

    Science.gov (United States)

    Williams, H. T.; Silbar, Richard R.

    1992-04-01

    We present a set of heuristic rules for algebraic solution of angular momentum recoupling problems. The general problem reduces to that of finding an optimal path from one binary tree (representing the angular momentum coupling scheme for the reduced matrix element) to another (representing the sub-integrals and spin sums to be done). The method lends itself to implementation on a microcomputer, and we have developed such an implementation using a dialect of LISP. We describe both how our code, called RACAH, works and how it appears to the user. We illustrate the use of RACAH for several transition and scattering amplitude matrix elements occurring in atomic, nuclear, and particle physics.

  7. ANGULAR MOMENTUM AND GALAXY FORMATION REVISITED

    International Nuclear Information System (INIS)

    Romanowsky, Aaron J.; Fall, S. Michael

    2012-01-01

    Motivated by a new wave of kinematical tracers in the outer regions of early-type galaxies (ellipticals and lenticulars), we re-examine the role of angular momentum in galaxies of all types. We present new methods for quantifying the specific angular momentum j, focusing mainly on the more challenging case of early-type galaxies, in order to derive firm empirical relations between stellar j * and mass M * (thus extending earlier work by Fall). We carry out detailed analyses of eight galaxies with kinematical data extending as far out as 10 effective radii, and find that data at two effective radii are generally sufficient to estimate total j * reliably. Our results contravene suggestions that ellipticals could harbor large reservoirs of hidden j * in their outer regions owing to angular momentum transport in major mergers. We then carry out a comprehensive analysis of extended kinematic data from the literature for a sample of ∼100 nearby bright galaxies of all types, placing them on a diagram of j * versus M * . The ellipticals and spirals form two parallel j * -M * tracks, with log-slopes of ∼0.6, which for the spirals are closely related to the Tully-Fisher relation, but for the ellipticals derives from a remarkable conspiracy between masses, sizes, and rotation velocities. The ellipticals contain less angular momentum on average than spirals of equal mass, with the quantitative disparity depending on the adopted K-band stellar mass-to-light ratios of the galaxies: it is a factor of ∼3-4 if mass-to-light ratio variations are neglected for simplicity, and ∼7 if they are included. We decompose the spirals into disks and bulges and find that these subcomponents follow j * -M * trends similar to the overall ones for spirals and ellipticals. The lenticulars have an intermediate trend, and we propose that the morphological types of galaxies reflect disk and bulge subcomponents that follow separate, fundamental j * -M * scaling relations. This provides a

  8. ANGULAR MOMENTUM AND GALAXY FORMATION REVISITED

    Energy Technology Data Exchange (ETDEWEB)

    Romanowsky, Aaron J. [University of California Observatories, 1156 High Street, Santa Cruz, CA 95064 (United States); Fall, S. Michael [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2012-12-15

    Motivated by a new wave of kinematical tracers in the outer regions of early-type galaxies (ellipticals and lenticulars), we re-examine the role of angular momentum in galaxies of all types. We present new methods for quantifying the specific angular momentum j, focusing mainly on the more challenging case of early-type galaxies, in order to derive firm empirical relations between stellar j{sub *} and mass M{sub *} (thus extending earlier work by Fall). We carry out detailed analyses of eight galaxies with kinematical data extending as far out as 10 effective radii, and find that data at two effective radii are generally sufficient to estimate total j{sub *} reliably. Our results contravene suggestions that ellipticals could harbor large reservoirs of hidden j{sub *} in their outer regions owing to angular momentum transport in major mergers. We then carry out a comprehensive analysis of extended kinematic data from the literature for a sample of {approx}100 nearby bright galaxies of all types, placing them on a diagram of j{sub *} versus M{sub *}. The ellipticals and spirals form two parallel j{sub *}-M{sub *} tracks, with log-slopes of {approx}0.6, which for the spirals are closely related to the Tully-Fisher relation, but for the ellipticals derives from a remarkable conspiracy between masses, sizes, and rotation velocities. The ellipticals contain less angular momentum on average than spirals of equal mass, with the quantitative disparity depending on the adopted K-band stellar mass-to-light ratios of the galaxies: it is a factor of {approx}3-4 if mass-to-light ratio variations are neglected for simplicity, and {approx}7 if they are included. We decompose the spirals into disks and bulges and find that these subcomponents follow j{sub *}-M{sub *} trends similar to the overall ones for spirals and ellipticals. The lenticulars have an intermediate trend, and we propose that the morphological types of galaxies reflect disk and bulge subcomponents that follow

  9. Characterization of the bell-shaped vibratory angular rate gyro.

    Science.gov (United States)

    Liu, Ning; Su, Zhong; Li, Qing; Fu, MengYin; Liu, Hong; Fan, JunFang

    2013-08-07

    The bell-shaped vibratory angular rate gyro (abbreviated as BVG) is a novel shell vibratory gyroscope, which is inspired by the Chinese traditional bell. It sensitizes angular velocity through the standing wave precession effect. The bell-shaped resonator is a core component of the BVG and looks like the millimeter-grade Chinese traditional bell, such as QianLong Bell and Yongle Bell. It is made of Ni43CrTi, which is a constant modulus alloy. The exciting element, control element and detection element are uniformly distributed and attached to the resonator, respectively. This work presents the design, analysis and experimentation on the BVG. It is most important to analyze the vibratory character of the bell-shaped resonator. The strain equation, internal force and the resonator's equilibrium differential equation are derived in the orthogonal curvilinear coordinate system. When the input angular velocity is existent on the sensitive axis, an analysis of the vibratory character is performed using the theory of thin shells. On this basis, the mode shape function and the simplified second order normal vibration mode dynamical equation are obtained. The coriolis coupling relationship about the primary mode and secondary mode is established. The methods of the signal processing and control loop are presented. Analyzing the impact resistance property of the bell-shaped resonator, which is compared with other shell resonators using the Finite Element Method, demonstrates that BVG has the advantage of a better impact resistance property. A reasonable means of installation and a prototypal gyro are designed. The gyroscopic effect of the BVG is characterized through experiments. Experimental results show that the BVG has not only the advantages of low cost, low power, long work life, high sensitivity, and so on, but, also, of a simple structure and a better impact resistance property for low and medium angular velocity measurements.

  10. Characterization of the Bell-Shaped Vibratory Angular Rate Gyro

    Directory of Open Access Journals (Sweden)

    Junfang Fan

    2013-08-01

    Full Text Available The bell-shaped vibratory angular rate gyro (abbreviated as BVG is a novel shell vibratory gyroscope, which is inspired by the Chinese traditional bell. It sensitizes angular velocity through the standing wave precession effect. The bell-shaped resonator is a core component of the BVG and looks like the millimeter-grade Chinese traditional bell, such as QianLong Bell and Yongle Bell. It is made of Ni43CrTi, which is a constant modulus alloy. The exciting element, control element and detection element are uniformly distributed and attached to the resonator, respectively. This work presents the design, analysis and experimentation on the BVG. It is most important to analyze the vibratory character of the bell-shaped resonator. The strain equation, internal force and the resonator's equilibrium differential equation are derived in the orthogonal curvilinear coordinate system. When the input angular velocity is existent on the sensitive axis, an analysis of the vibratory character is performed using the theory of thin shells. On this basis, the mode shape function and the simplified second order normal vibration mode dynamical equation are obtained. The coriolis coupling relationship about the primary mode and secondary mode is established. The methods of the signal processing and control loop are presented. Analyzing the impact resistance property of the bell-shaped resonator, which is compared with other shell resonators using the Finite Element Method, demonstrates that BVG has the advantage of a better impact resistance property. A reasonable means of installation and a prototypal gyro are designed. The gyroscopic effect of the BVG is characterized through experiments. Experimental results show that the BVG has not only the advantages of low cost, low power, long work life, high sensitivity, and so on, but, also, of a simple structure and a better impact resistance property for low and medium angular velocity measurements.

  11. Energy dependence of angular momentum transfer in post-collision interaction. Classical view

    Science.gov (United States)

    Gerchikov, L.; Sheinerman, S.

    2018-03-01

    A classical approach to the description of angular momentum transfer between the Auger electron and photoelectron in post-collision interaction is worked out. The results of the classical approach coincide with the quantum mechanical ones at the photoionization threshold. Besides, the approach developed provides a description of angular momentum transfer beyond the photoionization threshold. In particular, it is suitable in the energy region of comparable velocities of two emitted electrons.

  12. Observation of Coherent and Incoherent Dissociation Mechanisms in the Angular Distribution of Atomic Photofragment Alignment

    International Nuclear Information System (INIS)

    Bracker, A.S.; Lee, Y.T.; Bracker, A.S.; Wouters, E.R.; Suits, A.G.; Lee, Y.T.; Lee, Y.T.; Vasyutinskii, O.S.

    1998-01-01

    We have analyzed the recoil angle dependence of chlorine atom angular momentum alignment for the dissociation of chlorine molecules at 355nm. This angular distribution was isolated from ion image measurements, which map a three-dimensional velocity vector distribution of state-selectively-ionized photofragments into a two-dimensional spatial distribution. Using a general quantum mechanical method to simulate the alignment angular distribution, we show that there are clear contributions to alignment from both incoherent and coherent components of a perpendicular optical transition in the molecule. copyright 1998 The American Physical Society

  13. On Dunkl angular momenta algebra

    Energy Technology Data Exchange (ETDEWEB)

    Feigin, Misha [School of Mathematics and Statistics, University of Glasgow,15 University Gardens, Glasgow G12 8QW (United Kingdom); Hakobyan, Tigran [Yerevan State University,1 Alex Manoogian, 0025 Yerevan (Armenia); Tomsk Polytechnic University,Lenin Ave. 30, 634050 Tomsk (Russian Federation)

    2015-11-17

    We consider the quantum angular momentum generators, deformed by means of the Dunkl operators. Together with the reflection operators they generate a subalgebra in the rational Cherednik algebra associated with a finite real reflection group. We find all the defining relations of the algebra, which appear to be quadratic, and we show that the algebra is of Poincaré-Birkhoff-Witt (PBW) type. We show that this algebra contains the angular part of the Calogero-Moser Hamiltonian and that together with constants it generates the centre of the algebra. We also consider the gl(N) version of the subalgebra of the rational Cherednik algebra and show that it is a non-homogeneous quadratic algebra of PBW type as well. In this case the central generator can be identified with the usual Calogero-Moser Hamiltonian associated with the Coxeter group in the harmonic confinement.

  14. Phonons with orbital angular momentum

    International Nuclear Information System (INIS)

    Ayub, M. K.; Ali, S.; Mendonca, J. T.

    2011-01-01

    Ion accoustic waves or phonon modes are studied with orbital angular momentum (OAM) in an unmagnetized collissionless uniform plasma, whose constituents are the Boltzmann electrons and inertial ions. For this purpose, we have employed the fluid equations to obtain a paraxial equation in terms of ion density perturbations and discussed its Gaussian beam and Laguerre-Gauss (LG) beam solutions. Furthermore, an approximate solution for the electrostatic potential problem is presented, allowing to express the components of the electric field in terms of LG potential perturbations. The energy flux due to phonons is also calculated and the corresponding OAM is derived. Numerically, it is shown that the parameters such as azimuthal angle, radial and angular mode numbers, and beam waist, strongly modify the profiles of the phonon LG potential. The present results should be helpful in understanding the phonon mode excitations produced by Brillouin backscattering of laser beams in a uniform plasma.

  15. Angular momentum in QGP holography

    Directory of Open Access Journals (Sweden)

    Brett McInnes

    2014-10-01

    Full Text Available The quark chemical potential is one of the fundamental parameters describing the quark–gluon plasma produced by sufficiently energetic heavy-ion collisions. It is not large at the extremely high temperatures probed by the LHC, but it plays a key role in discussions of the beam energy scan programmes at the RHIC and other facilities. On the other hand, collisions at such energies typically (that is, in peripheral collisions give rise to very high values of the angular momentum density. Here we explain that holographic estimates of the quark chemical potential of a rotating sample of plasma can be very considerably improved by taking the angular momentum into account.

  16. Angular Motion Estimation Using Dynamic Models in a Gyro-Free Inertial Measurement Unit

    Directory of Open Access Journals (Sweden)

    Otmar Loffeld

    2012-04-01

    Full Text Available In this paper, we summarize the results of using dynamic models borrowed from tracking theory in describing the time evolution of the state vector to have an estimate of the angular motion in a gyro-free inertial measurement unit (GF-IMU. The GF-IMU is a special type inertial measurement unit (IMU that uses only a set of accelerometers in inferring the angular motion. Using distributed accelerometers, we get an angular information vector (AIV composed of angular acceleration and quadratic angular velocity terms. We use a Kalman filter approach to estimate the angular velocity vector since it is not expressed explicitly within the AIV. The bias parameters inherent in the accelerometers measurements’ produce a biased AIV and hence the AIV bias parameters are estimated within an augmented state vector. Using dynamic models, the appended bias parameters of the AIV become observable and hence we can have unbiased angular motion estimate. Moreover, a good model is required to extract the maximum amount of information from the observation. Observability analysis is done to determine the conditions for having an observable state space model. For higher grades of accelerometers and under relatively higher sampling frequency, the error of accelerometer measurements is dominated by the noise error. Consequently, simulations are conducted on two models, one has bias parameters appended in the state space model and the other is a reduced model without bias parameters.

  17. AngularJS test-driven development

    CERN Document Server

    Chaplin, Tim

    2015-01-01

    This book is for developers who want to learn about AngularJS development by applying testing techniques. You are assumed to have a basic knowledge and understanding of HTML, JavaScript, and AngularJS.

  18. Angular Momentum of Topologically Structured Darkness.

    Science.gov (United States)

    Alperin, Samuel N; Siemens, Mark E

    2017-11-17

    We theoretically analyze and experimentally measure the extrinsic angular momentum contribution of topologically structured darkness found within fractional vortex beams, and show that this structured darkness can be explained by evanescent waves at phase discontinuities in the generating optic. We also demonstrate the first direct measurement of the intrinsic orbital angular momentum of light with both intrinsic and extrinsic angular momentum, and explain why the total orbital angular momenta of fractional vortices do not match the winding number of their generating phases.

  19. AngularJS web application development

    CERN Document Server

    Darwin, Peter Bacon

    2013-01-01

    The book will be a step-by-step guide showing the readers how to build a complete web app with AngularJSJavaScript developers who want to learn AngularJS for developing web apps. Knowledge of JavaScript and HTML is expected. No knowledge of AngularJS is required.

  20. Optical angular momentum in classical electrodynamics

    Science.gov (United States)

    Mansuripur, Masud

    2017-06-01

    Invoking Maxwell’s classical equations in conjunction with expressions for the electromagnetic (EM) energy, momentum, force, and torque, we use a few simple examples to demonstrate the nature of the EM angular momentum. The energy and the angular momentum of an EM field will be shown to have an intimate relationship; a source radiating EM angular momentum will, of necessity, pick up an equal but opposite amount of mechanical angular momentum; and the spin and orbital angular momenta of the EM field, when absorbed by a small particle, will be seen to elicit different responses from the particle.

  1. Dependency injection with AngularJS

    CERN Document Server

    Knol, Alex

    2013-01-01

    This book is a practical, hands-on approach to using dependency injection and implementing test-driven development using AngularJS. Dependency Injection with AngularJS is aimed at developers who are aware of AngularJS but need to get started with using it in real life applications. Also, developers who want to get into test-driven development with AngularJS can use this book as practical guide. Even if you know about dependency injection, it can serve as a good reference on how it is used within AngularJS. Readers are expected to have some experience with JavaScript.

  2. The role of angular momentum conservation law in statistical mechanics

    Directory of Open Access Journals (Sweden)

    I.M. Dubrovskii

    2008-12-01

    Full Text Available Within the limits of Khinchin ideas [A.Y. Khinchin, Mathematical Foundation of Statistical Mechanics. NY, Ed. Dover, 1949] the importance of momentum and angular momentum conservation laws was analyzed for two cases: for uniform magnetic field and when magnetic field is absent. The law of momentum conservation does not change the density of probability distribution in both cases, just as it is assumed in the conventional theory. It is shown that in systems where the kinetic energy depends only on particle momenta canonically conjugated with Cartesian coordinates being their diagonal quadric form,the angular momentum conservation law changes the density of distribution of the system only in case the full angular momentum of a system is not equal to zero. In the gas of charged particles in a uniform magnetic field the density of distribution also varies if the angular momentum is zero [see Dubrovskii I.M., Condensed Matter Physics, 2206, 9, 23]. Two-dimensional gas of charged particles located within a section of an endless strip filled with gas in magnetic field is considered. Under such conditions the angular momentum is not conserved. Directional particle flows take place close to the strip boundaries, and, as a consequence, the phase trajectory of the considered set of particles does not remain within the limited volume of the phase space. In order to apply a statistical thermodynamics method, it was suggested to consider near-boundary trajectories relative to a reference system that moves uniformly. It was shown that if the diameter of an orbit having average thermal energy is much smaller than a strip width, the corrections to thermodynamic functions are small depending on magnetic field. Only the average velocity of near-boundary particles that form near-boundary electric currents creating the paramagnetic moment turn out to be essential.

  3. Angular Rate Optimal Design for the Rotary Strapdown Inertial Navigation System

    Directory of Open Access Journals (Sweden)

    Fei Yu

    2014-04-01

    Full Text Available Due to the characteristics of high precision for a long duration, the rotary strapdown inertial navigation system (RSINS has been widely used in submarines and surface ships. Nowadays, the core technology, the rotating scheme, has been studied by numerous researchers. It is well known that as one of the key technologies, the rotating angular rate seriously influences the effectiveness of the error modulating. In order to design the optimal rotating angular rate of the RSINS, the relationship between the rotating angular rate and the velocity error of the RSINS was analyzed in detail based on the Laplace transform and the inverse Laplace transform in this paper. The analysis results showed that the velocity error of the RSINS depends on not only the sensor error, but also the rotating angular rate. In order to minimize the velocity error, the rotating angular rate of the RSINS should match the sensor error. One optimal design method for the rotating rate of the RSINS was also proposed in this paper. Simulation and experimental results verified the validity and superiority of this optimal design method for the rotating rate of the RSINS.

  4. Angular Positioning Sensor for Space Mechanisms

    Science.gov (United States)

    Steiner, Nicolas; Chapuis, Dominique

    2013-09-01

    Angular position sensors are used on various rotating mechanisms such as solar array drive mechanisms, antenna pointing mechanisms, scientific instruments, motors or actuators.Now a days, potentiometers and encoders are mainly used for angular measurement purposes. Both of them have their own pros and cons.As alternative, Ruag Space Switzerland Nyon (RSSN) is developing and qualifying two innovative technologies of angular position sensors which offer easy implementation, medium to very high lifetime and high flexibility with regards to the output signal shape/type.The Brushed angular position sensor uses space qualified processes which are already flying on RSSN's sliprings for many years. A large variety of output signal shape can be implemented to fulfill customer requirements (digital, analog, customized, etc.).The contactless angular position sensor consists in a new radiation hard Application Specific Integrated Circuit (ASIC) based on the Hall effect and providing the angular position without complex processing algorithm.

  5. Oral candidiasis and angular cheilitis.

    Science.gov (United States)

    Sharon, Victoria; Fazel, Nasim

    2010-01-01

    Candidiasis, an often encountered oral disease, has been increasing in frequency. Most commonly caused by the overgrowth of Candida albicans, oral candidiasis can be divided into several categories including acute and chronic forms, and angular cheilitis. Risk factors for the development of oral candidiasis include immunosuppression, wearing of dentures, pharmacotherapeutics, smoking, infancy and old age, endocrine dysfunction, and decreased salivation. Oral candidiasis may be asymptomatic. More frequently, however, it is physically uncomfortable, and the patient may complain of burning mouth, dysgeusia, dysphagia, anorexia, and weight loss, leading to nutritional deficiency and impaired quality of life. A plethora of antifungal treatments are available. The overall prognosis of oral candidiasis is good, and rarely is the condition life threatening with invasive or recalcitrant disease.

  6. Management of angular cheilitis for children

    Directory of Open Access Journals (Sweden)

    Fajriani Fajriani

    2016-06-01

    Full Text Available Angular cheilitis is one type of oral soft tissue disease that can occur in both children and adults, the condition is characterized by cracks and inflammation in both corners of the mouth. Although this disease does not cause severe disruption but quite disturbing activity and also one's physical appearance. Angular cheilitis light will disappear on their own over time.Severe conditions that can cause pain and bleading. aims to give feedback on peers about managment angular cheilitis in children.

  7. A neural circuit architecture for angular integration in Drosophila.

    Science.gov (United States)

    Green, Jonathan; Adachi, Atsuko; Shah, Kunal K; Hirokawa, Jonathan D; Magani, Pablo S; Maimon, Gaby

    2017-06-01

    Many animals keep track of their angular heading over time while navigating through their environment. However, a neural-circuit architecture for computing heading has not been experimentally defined in any species. Here we describe a set of clockwise- and anticlockwise-shifting neurons in the Drosophila central complex whose wiring and physiology provide a means to rotate an angular heading estimate based on the fly's angular velocity. We show that each class of shifting neurons exists in two subtypes, with spatiotemporal activity profiles that suggest different roles for each subtype at the start and end of tethered-walking turns. Shifting neurons are required for the heading system to properly track the fly's heading in the dark, and stimulation of these neurons induces predictable shifts in the heading signal. The central features of this biological circuit are analogous to those of computational models proposed for head-direction cells in rodents and may shed light on how neural systems, in general, perform integration.

  8. Transverse and longitudinal angular momenta of light

    Energy Technology Data Exchange (ETDEWEB)

    Bliokh, Konstantin Y., E-mail: k.bliokh@gmail.com [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Nonlinear Physics Centre, RSPhysE, The Australian National University, Canberra, ACT 0200 (Australia); Nori, Franco [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Physics Department, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2015-08-26

    We review basic physics and novel types of optical angular momentum. We start with a theoretical overview of momentum and angular momentum properties of generic optical fields, and discuss methods for their experimental measurements. In particular, we describe the well-known longitudinal (i.e., aligned with the mean momentum) spin and orbital angular momenta in polarized vortex beams. Then, we focus on the transverse (i.e., orthogonal to the mean momentum) spin and orbital angular momenta, which were recently actively discussed in theory and observed in experiments. First, the recently-discovered transverse spin  angular momenta appear in various structured fields: evanescent waves, interference fields, and focused beams. We show that there are several kinds of transverse spin angular momentum, which differ strongly in their origins and physical properties. We describe extraordinary features of the transverse optical spins and overview recent experiments. In particular, the helicity-independent transverse spin inherent in edge evanescent waves offers robust spin–direction coupling at optical interfaces (the quantum spin Hall effect of light). Second, we overview the transverse orbital angular momenta of light, which can be both extrinsic and intrinsic. These two types of the transverse orbital angular momentum are produced by spatial shifts of the optical beams (e.g., in the spin Hall effect of light) and their Lorentz boosts, respectively. Our review is underpinned by a unified theory of the angular momentum of light based on the canonical momentum and spin densities, which avoids complications associated with the separation of spin and orbital angular momenta in the Poynting picture. It allows us to construct a comprehensive classification of all known optical angular momenta based on their key parameters and main physical properties.

  9. An angular acceleration sensor inspired by the vestibular system with a fully circular fluid-channel and thermal read-out

    NARCIS (Netherlands)

    Groenesteijn, Jarno; Droogendijk, H.; de Boer, Meint J.; Sanders, Remco G.P.; Wiegerink, Remco J.; Krijnen, Gijsbertus J.M.

    2014-01-01

    We report on an angular accelerometer based on the semicircular channels of the vestibular system. The accelerometer consists of a water-filled circular tube, wherein the fluid flow velocity is measured thermally as a representation for the external angular acceleration. Measurements show a linear

  10. Electromagnetic radiation in a medium with a velocity gradient

    Science.gov (United States)

    Gladyshev, V. O.; Tereshin, A. A.; Bazleva, D. D.

    2016-04-01

    A relativistic expression has been obtained for the curvature of trajectory of the wave vector of an electromagnetic wave in a moving optically transparent medium. It has been shown that the curvature of the trajectory and angular deviation of rays appear in a homogeneous isotropic medium if the gradient of the velocity field in the medium is nonzero. The bending of the trajectory in the medium with the velocity gradient is a firstorder effect in the ratio u/ c.

  11. Angular momentum transfer in incomplete fusion

    Indian Academy of Sciences (India)

    fusion reactions. The angular momentum of the intermediate nucleus formed in incomplete fusion was deduced from the isomeric cross-section ratio by considering the statistical de- excitation of the incompletely fused composite nucleus. The data show that incomplete fusion is associated with angular momenta slightly ...

  12. Responsive web design with AngularJS

    CERN Document Server

    Patel, Sandeep Kumar

    2014-01-01

    If you are an AngularJS developer who wants to learn about responsive web application development, this book is ideal for you. Responsive Web Design with AngularJS is intended for web developers or designers with a basic knowledge of HTML, CSS, and JavaScript.

  13. Angular momentum transfer in incomplete fusion

    Indian Academy of Sciences (India)

    The angular momentum of the intermediate nucleus formed in incomplete fusion was deduced from the isomeric cross-section ratio by considering the statistical de-excitation of the incompletely fused composite nucleus. The data show that incomplete fusion is associated with angular momenta slightly smaller than critical ...

  14. Accelerated rotation with orbital angular momentum modes

    CSIR Research Space (South Africa)

    Schulze, C

    2015-04-01

    Full Text Available A 91, 043821 (2015) Accelerated rotation with orbital angular momentum modes Christian Schulze, Filippus S. Roux, Angela Dudley, Ronald Rop, Michael Duparr´e, and Andrew Forbes Abstract: We introduce a class of light field that angularly...

  15. Dijet angular distributions at D0

    International Nuclear Information System (INIS)

    Fatyga, M.K.

    1996-09-01

    Measurements of the dijet angular distributions are relatively insensitive to parton distribution functions and thus offer an excellent method of testing the LO and NLO predictions of perturbative QCD. The authors present measurements of the dijet angular distributions for |η| < 3.0 in p anti p collisions at √s = 1.8 TeV

  16. Experimental determination of high angular momentum states

    International Nuclear Information System (INIS)

    Barreto, J.L.V.

    1985-01-01

    The current knowledge of the atomic nucleus structure is summarized. A short abstract of the nuclear properties at high angular momentum and a more detailed description of the experimental methods used in the study of high angular momenta is made. (L.C.) [pt

  17. Concepts of radial and angular kinetic energies

    DEFF Research Database (Denmark)

    Dahl, Jens Peder; Schleich, W.P.

    2002-01-01

    We consider a general central-field system in D dimensions and show that the division of the kinetic energy into radial and angular parts proceeds differently in the wave-function picture and the Weyl-Wigner phase-space picture, Thus, the radial and angular kinetic energies are different quantities...

  18. ANGULAR MOMENTUM IN GIANT MOLECULAR CLOUDS. I. THE MILKY WAY

    International Nuclear Information System (INIS)

    Imara, Nia; Blitz, Leo

    2011-01-01

    We present a detailed analysis comparing the velocity fields in molecular clouds and the atomic gas that surrounds them in order to address the origin of the gradients. To that end, we present first-moment intensity-weighted velocity maps of the molecular clouds and surrounding atomic gas. The maps are made from high-resolution 13 CO observations and 21 cm observations from the Leiden/Argentine/Bonn Galactic H I Survey. We find that (1) the atomic gas associated with each molecular cloud has a substantial velocity gradient-ranging from 0.02 to 0.07 km s -1 pc -1 -whether or not the molecular cloud itself has a substantial linear gradient. (2) If the gradients in the molecular and atomic gas were due to rotation, this would imply that the molecular clouds have less specific angular momentum than the surrounding H I by a factor of 1-6. (3) Most importantly, the velocity gradient position angles in the molecular and atomic gas are generally widely separated-by as much as 130 deg. in the case of the Rosette molecular cloud. This result argues against the hypothesis that molecular clouds formed by simple top-down collapse from atomic gas.

  19. Perturbed angular correlations and distributions

    International Nuclear Information System (INIS)

    Makaryunas, K.

    1976-01-01

    The present index comprises original works and review papers on the perturbed angular correlations (PAC) and distributions (PAD). The articles published in the Soviet and foreign journals as well as the materials of conferences, monographs and collections published in the USSR and abroad, the preprints produced by various institutes and abstracts of disertations are included from 1948 up to 1973. The whole material compiled in this index is divided into three parts. Part one is a bibliographic index. All papers in this part are divided into three sections. Section one comprises the papers devoted to the theoretical works on PAC, review papers, monographs, materials of conferences. Section two deals with the works of methodical character where correlation spectrometers as well as the treatment of experimental data are described. In section three experimental works with concrete nuclei are compiled. Part two gives the characteristic of works performed with concrete nuclei. This part is presented in the form of the table in which the works are systematized according to the chemical elements and isotopes. The table shows the characteristics of the nuclear levels used in the investigations by PAC as well as brief characteristics of experiments and results obtained. Part three - appendix contains alphabetic index of the authors, the list of the used editions with the abbreviations of the titles of these editions. The lists indicating the dynamic of the quantity of works on PAC and the distribution according to the literature sources are also given

  20. Latitudinal Transport of Angular Momentum by Cellular Flows Observed with MDI

    Science.gov (United States)

    Hathaway, David H.; Gilman, Peter A.; Beck, John G.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    We have analyzed Doppler velocity images from the MDI instrument on SOHO to determine the latitudinal transport of angular momentum by the cellular photospheric flows. Doppler velocity images from 60-days in May to July of 1996 were processed to remove the p-mode oscillations, the convective blue shift, the axisymmetric flows, and any instrumental artifacts. The remaining cellular flows were examined for evidence of latitudinal angular momentum transport. Small cells show no evidence of any such transport. Cells the size of supergranules (30,000 km in diameter) show strong evidence for a poleward transport of angular momentum. This would be expected if supergranules are influenced by the Coriolis force, and if the cells are elongated in an east-west direction. We find good evidence for just such an east-west elongation of the supergranules. This elongation may be the result of differential rotation shearing the cellular structures. Data simulations of this effect support the conclusion that elongated supergranules transport angular momentum from the equator toward the poles, Cells somewhat larger than supergranules do not show evidence for this poleward transport. Further analysis of the data is planned to determine if the direction of angular momentum transport reverses for even larger cellular structures. The Sun's rapidly rotating equator must be maintained by such transport somewhere within the convection zone.

  1. Bar formation in disk galaxies, and the normalized angular momentum of the bulge

    Energy Technology Data Exchange (ETDEWEB)

    Zasov, A.V.

    1985-09-01

    In 1971 Polyachenko et al. suggested that the spheroidal bulge in a spiral galaxy would retain a biaxial shape unless its normalized angular momentum, defined as M = KM/sub b//sup -5/3/ (K is the ordinary angular momentum and M/sub b/ the mass of the bulge), exceeds some critical value; in that event a triaxial ellipsoid: a bar: would develop. This proposal is in fact consistent with bulge rotational velocities observed in disk-type systems. The bar presumably represents a bulge component having a high M value.

  2. Radiofrequency encoded angular-resolved light scattering

    DEFF Research Database (Denmark)

    Buckley, Brandon W.; Akbari, Najva; Diebold, Eric D.

    2015-01-01

    The sensitive, specific, and label-free classification of microscopic cells and organisms is one of the outstanding problems in biology. Today, instruments such as the flow cytometer use a combination of light scatter measurements at two distinct angles to infer the size and internal complexity...... of cells at rates of more than 10,000 per second. However, by examining the entire angular light scattering spectrum it is possible to classify cells with higher resolution and specificity. Current approaches to performing these angular spectrum measurements all have significant throughput limitations...... Encoded Angular-resolved Light Scattering (REALS), this technique multiplexes angular light scattering in the radiofrequency domain, such that a single photodetector captures the entire scattering spectrum from a particle over approximately 100 discrete incident angles on a single shot basis. As a proof...

  3. Optical communication beyond orbital angular momentum

    CSIR Research Space (South Africa)

    Trichili, A

    2016-06-01

    Full Text Available Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission...

  4. Dynamical Model of Fission Fragment Angular Distribution

    Science.gov (United States)

    Drozdov, V. A.; Eremenko, D. O.; Fotina, O. V.; Platonov, S. Yu.; Yuminov, O. A.; Giardina, G.; Taccone, A.

    2002-01-01

    A dynamical model of fission fragment angular distributions is suggested. The model allows one to calculate fission fragment angular distributions, prescission light particle multyplicities, evaporation residue cross sections etc. for the cases of decay of hot and rotating heavy nuclei. The experimental data on angular anisotropies of fission fragments and prescission neutron multiplicities are analyzed for the 16O + 208Pb, 232Th, 248Cm and 238U reactions at the energies of the incident 16O ions ranging from 90 to 160 MeV. This analysis allows us to extract both the nuclear friction coefficient value and the relaxation time for the tilting mode. It is also demonstrated that the angular distributions are sensitive to the deformation dependence of the nuclear friction.

  5. Amplitude damping channel for orbital angular momentum

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2010-03-01

    Full Text Available Since the pioneering work on the entanglement of the orbital angular momentum (OAM) states of light, much attention has been devoted to the subject, with particular attention into the quantum aspects of information processing using OAM. Furthermore...

  6. Mastering AngularJD for .NET developers

    CERN Document Server

    Majid, Mohammad Wadood

    2015-01-01

    This book is envisioned for traditional developers and programmers who want to develop client-side applications using the AngularJS framework and ASP.NET Web API 2 with Visual Studio. .NET developers who have already built web applications or web services and who have a fundamental knowledge of HTML, JavaScript, and CSS and want to explore single-page applications will also find this guide useful. Basic knowledge of AngularJS would be helpful.

  7. Partial angular coherence and the angular Schmidt spectrum of entangled two-photon fields

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Anand Kumar; Boyd, Robert W. [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Agarwal, Girish S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)

    2011-12-15

    We study partially coherent fields that have a coherent-mode representation in the orbital-angular-momentum-mode basis. For such fields, we introduce the concepts of the angular coherence function and the coherence angle. Such fields are naturally produced by the process of parametric down-conversion--a second-order nonlinear optical process in which a pump photon breaks up into two entangled photons, known as the signal and idler photons. We show that the angular coherence functions of the signal and idler fields are directly related to the angular Schmidt (spiral) spectrum of the down-converted two-photon field and thus that the angular Schmidt spectrum can be measured directly by measuring the angular coherence function of either the signal or the idler field, without requiring coincidence detection.

  8. Fuzzy Logic Velocity Control of a Biped Robot Locomotion and Simulation

    Directory of Open Access Journals (Sweden)

    Arif Ankarali

    2012-10-01

    Full Text Available In this paper, fuzzy logic velocity control of a biped robot to generate gait is studied. The system considered in this study has six degrees of freedom with hip, knee and ankle joints. The joint angular positions are determined utilizing the Cartesian coordinate information of the joints obtained by using camera captured data of the motion. The first derivatives of the calculated joint angular positions are applied as the reference angular velocity input to the fuzzy controllers of the joint servomotors to generate a gait motion. The assumed motion for the biped robot is horizontal walking on a flat surface. The actuated joints are hip, knee and ankle joints which are driven by DC servomotors. The calculated angular velocities of the joints from camera captured motion data are utilized to get the driving velocity functions of the model as sine functions. These functions are applied to the fuzzy controller as the reference angular velocity inputs. The control signals produced by the fuzzy controllers are applied to the servomotors and then the response of the servomotor block is introduced as an input to the SimMechanics model of the biped robot. The simulation results are provided which evaluate the effectiveness of the fuzzy logic controller on joint velocities to generate gait motion.

  9. Control of Rotational Energy and Angular Momentum Orientation with an Optical Centrifuge

    Science.gov (United States)

    Ogden, Hannah M.; Murray, Matthew J.; Mullin, Amy S.

    2017-04-01

    We use an optical centrifuge to trap and spin molecules to an angular frequency of 30 THz with oriented angular momenta and extremely high rotational energy and then investigate their subsequent collision dynamics with transient high resolution IR spectroscopy. The optical centrifuge is formed by combining oppositely-chirped pulses of 800 nm light, and overlapping them spatially and temporally. Polarization-sensitive Doppler-broadened line profiles characterize the anisotropic kinetic energy release of the super rotor molecules, showing that they behave like molecular gyroscopes. Studies are reported for collisions of CO2 super rotors with CO2, He and Ar. These studies reveal how mass, velocity and rotational adiabaticity impact the angular momentum relaxation and reorientation. Quantum scattering calculations provide insight into the J-specific collision cross sections that control the relaxation. NSF-CHE 105 8721.

  10. Rotational Angles and Velocities During Down the Line and Diagonal Across Court Volleyball Spikes

    Directory of Open Access Journals (Sweden)

    Justin R. Brown

    2014-05-01

    Full Text Available The volleyball spike is an explosive movement that is frequently used to end a rally and earn a point. High velocity spikes are an important skill for a successful volleyball offense. Although the influence of vertical jump height and arm velocity on spiked ball velocity (SBV have been investigated, little is known about the relationship of shoulder and hip angular kinematics with SBV. Other sport skills, like the baseball pitch share similar movement patterns and suggest trunk rotation is important for such movements. The purpose of this study was to examine the relationship of both shoulder and hip angular kinematics with ball velocity during the volleyball spike. Methods: Fourteen Division I collegiate female volleyball players executed down the line (DL and diagonally across-court (DAC spikes in a laboratory setting to measure shoulder and hip angular kinematics and velocities. Each spike was analyzed using a 10 Camera Raptor-E Digital Real Time Camera System.  Results: DL SBV was significantly greater than for DAC, respectively (17.54±2.35 vs. 15.97±2.36 m/s, p<0.05.  The Shoulder Hip Separation Angle (S-HSA, Shoulder Angular Velocity (SAV, and Hip Angular Velocity (HAV were all significantly correlated with DAC SBV. S-HSA was the most significant predictor of DAC SBV as determined by regression analysis.  Conclusions: This study provides support for a relationship between a greater S-HSA and SBV. Future research should continue to 1 examine the influence of core training exercise and rotational skill drills on SBV and 2 examine trunk angular velocities during various types of spikes during play.

  11. Transverse angular momentum in topological photonic crystals

    Science.gov (United States)

    Deng, Wei-Min; Chen, Xiao-Dong; Zhao, Fu-Li; Dong, Jian-Wen

    2018-01-01

    Engineering local angular momentum of structured light fields in real space enables applications in many fields, in particular, the realization of unidirectional robust transport in topological photonic crystals with a non-trivial Berry vortex in momentum space. Here, we show transverse angular momentum modes in silicon topological photonic crystals when considering transverse electric polarization. Excited by a chiral external source with either transverse spin angular momentum or transverse phase vortex, robust light flow propagating along opposite directions is observed in several kinds of sharp-turn interfaces between two topologically-distinct silicon photonic crystals. A transverse orbital angular momentum mode with alternating phase vortex exists at the boundary of two such photonic crystals. In addition, unidirectional transport is robust to the working frequency even when the ring size or location of the pseudo-spin source varies in a certain range, leading to the superiority of the broadband photonic device. These findings enable one to make use of transverse angular momentum, a kind of degree of freedom, to achieve unidirectional robust transport in the telecom region and other potential applications in integrated photonic circuits, such as on-chip robust delay lines.

  12. Angular distribution of oriented nucleus fission neutrons

    International Nuclear Information System (INIS)

    Barabanov, A.L.; Grechukhin, D.P.

    1982-01-01

    Calculations of anisotropy of angular distribution of oriented 235 U nuclei thermal fission neutrons have been carried out. the neutrons were assumed to evaporate isotropically by completely accelerated fragements in the fragment system with only its small part, i. e. fission-producing neutrons, emitted at the moment of neck break. It has been found out that at low energies of neutrons Esub(n)=1-2 MeV the sensitivity of the angular distribution anisotropy to variations of spectrum of neutron evaporation from fragments and the magnitude of a share of fission-producing neutrons reaches approximately 100%, which at high energies, Esub(n) > 5 MeV it does not exceed approximately 20%. Therefore the angular distribution of fast neutrons to a greater degree of confidence may be used for restoring the angular distribution anisotropy of fragments while the angular distribution of low energy neutrons may be used for deriving information on the fission process, but only in case 6f the experiment accuracy is better than approximately 3%

  13. Angular Spectral Analysis and Lowpass Filtering of Aeromagnetic ...

    African Journals Online (AJOL)

    Total-field aeromagnetic data over the western half of the Bornu basin and its surrounding areas were analyzed using angular spectral analysis, upward continuation and lowpass filtering techniques. Results revealed several angular spectral peaks at various angular orientations. The angular orientations correlated with the ...

  14. Data-oriented development with AngularJS

    CERN Document Server

    Waikar, Manoj

    2015-01-01

    This book helps beginner-level AngularJS developers organize AngularJS applications by discussing important AngularJS concepts and best practices. If you are an experienced AngularJS developer but haven't written directives or haven't created custom HTML controls before, then this book is ideal for you.

  15. Close binary evolution. II. Impact of tides, wind magnetic braking, and internal angular momentum transport

    Science.gov (United States)

    Song, H. F.; Meynet, G.; Maeder, A.; Ekström, S.; Eggenberger, P.; Georgy, C.; Qin, Y.; Fragos, T.; Soerensen, M.; Barblan, F.; Wade, G. A.

    2018-01-01

    Context. Massive stars with solar metallicity lose important amounts of rotational angular momentum through their winds. When a magnetic field is present at the surface of a star, efficient angular momentum losses can still be achieved even when the mass-loss rate is very modest, at lower metallicities, or for lower-initial-mass stars. In a close binary system, the effect of wind magnetic braking also interacts with the influence of tides, resulting in a complex evolution of rotation. Aims: We study the interactions between the process of wind magnetic braking and tides in close binary systems. Methods: We discuss the evolution of a 10 M⊙ star in a close binary system with a 7 M⊙ companion using the Geneva stellar evolution code. The initial orbital period is 1.2 days. The 10 M⊙ star has a surface magnetic field of 1 kG. Various initial rotations are considered. We use two different approaches for the internal angular momentum transport. In one of them, angular momentum is transported by shear and meridional currents. In the other, a strong internal magnetic field imposes nearly perfect solid-body rotation. The evolution of the primary is computed until the first mass-transfer episode occurs. The cases of different values for the magnetic fields and for various orbital periods and mass ratios are briefly discussed. Results: We show that, independently of the initial rotation rate of the primary and the efficiency of the internal angular momentum transport, the surface rotation of the primary will converge, in a time that is short with respect to the main-sequence lifetime, towards a slowly evolving velocity that is different from the synchronization velocity. This "equilibrium angular velocity" is always inferior to the angular orbital velocity. In a given close binary system at this equilibrium stage, the difference between the spin and the orbital angular velocities becomes larger when the mass losses and/or the surface magnetic field increase. The

  16. Sensor Data Quality and Angular Rate Down-Selection Algorithms on SLS EM-1

    Science.gov (United States)

    Park, Thomas; Oliver, Emerson; Smith, Austin

    2018-01-01

    The NASA Space Launch System Block 1 launch vehicle is equipped with an Inertial Navigation System (INS) and multiple Rate Gyro Assemblies (RGA) that are used in the Guidance, Navigation, and Control (GN&C) algorithms. The INS provides the inertial position, velocity, and attitude of the vehicle along with both angular rate and specific force measurements. Additionally, multiple sets of co-located rate gyros supply angular rate data. The collection of angular rate data, taken along the launch vehicle, is used to separate out vehicle motion from flexible body dynamics. Since the system architecture uses redundant sensors, the capability was developed to evaluate the health (or validity) of the independent measurements. A suite of Sensor Data Quality (SDQ) algorithms is responsible for assessing the angular rate data from the redundant sensors. When failures are detected, SDQ will take the appropriate action and disqualify or remove faulted sensors from forward processing. Additionally, the SDQ algorithms contain logic for down-selecting the angular rate data used by the GN&C software from the set of healthy measurements. This paper provides an overview of the algorithms used for both fault-detection and measurement down selection.

  17. Visual reaction times during prolonged angular acceleration parallel the subjective perception of rotation

    Science.gov (United States)

    Mattson, D. L.

    1975-01-01

    The effect of prolonged angular acceleration on choice reaction time to an accelerating visual stimulus was investigated, with 10 commercial airline pilots serving as subjects. The pattern of reaction times during and following acceleration was compared with the pattern of velocity estimates reported during identical trials. Both reaction times and velocity estimates increased at the onset of acceleration, declined prior to the termination of acceleration, and showed an aftereffect. These results are inconsistent with the torsion-pendulum theory of semicircular canal function and suggest that the vestibular adaptation is of central origin.

  18. Angular correlations and high energy evolution

    International Nuclear Information System (INIS)

    Kovner, Alex; Lublinsky, Michael

    2011-01-01

    We address the question of to what extent JIMWLK evolution is capable of taking into account angular correlations in a high energy hadronic wave function. Our conclusion is that angular (and indeed other) correlations in the wave function cannot be reliably calculated without taking into account Pomeron loops in the evolution. As an example we study numerically the energy evolution of angular correlations between dipole scattering amplitudes in the framework of the large N c approximation to JIMWLK evolution (the 'projectile dipole model'). Target correlations are introduced via averaging over an (isotropic) ensemble of anisotropic initial conditions. We find that correlations disappear very quickly with rapidity even inside the saturation radius. This is in accordance with our physical picture of JIMWLK evolution. The actual correlations inside the saturation radius in the target QCD wave function, on the other hand, should remain sizable at any rapidity.

  19. Signal processing related to the vestibulo-ocular reflex during combined angular rotation and linear translation of the head

    Science.gov (United States)

    McCrea, R. A.; Chen-Huang, C.; Peterson, B. W. (Principal Investigator)

    1999-01-01

    The contributions of vestibular nerve afferents and central vestibular pathways to the angular (AVOR) and linear (LVOR) vestibulo-ocular reflex were studied in squirrel monkeys during fixation of near and far targets. Irregular vestibular afferents did not appear to be necessary for the LVOR, since when they were selectively silenced with galvanic currents the LVOR was essentially unaffected during both far- and near-target viewing. The linear translation signals generated by secondary AVOR neurons in the vestibular nuclei were, on average, in phase with head velocity, inversely related to viewing distance, and were nearly as strong as AVOR-related signals. We suggest that spatial-temporal transformation of linear head translation signals to angular eye velocity commands is accomplished primarily by the addition of viewing distance multiplied, centrally integrated, otolith regular afferent signals to angular VOR pathways.

  20. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  1. COMPARATIVE MEASUREMENTS OF HEAD ANGULAR MOVEMENTS USING A CAMERA SYSTEM AND A GYROSCOPE SYSTEM

    Directory of Open Access Journals (Sweden)

    Vladimir Socha

    2014-08-01

    Full Text Available Assessments of body-segment angular movements are very important in the rehabilitation process. Head angular movements are measured and analyzed for use in studies of stability and posture. However, there is no methodology for assessing angular movements of the head, and it has not been verified whether data measured by fundamentally different MoCap systems will lead to the same results. In this study, we used a camera system and a 3DOF orientation tracker placed on the subject’s head, and measured inclination (roll and flexion (pitch during quiet stance. The total length and the mean velocity of the traces of the pitch versus roll plots were used to measure and analyze head orientation. Using these methods, we are able to model the distribution of the measured 2D data, and to evaluate stability and posture. The results show that the total lengths and the mean velocities related to the 3DOF orientation tracker do not differ significantly from the total lengths and the mean velocities of traces related to the IR medical camera. We also found that the systems are not interchangeable, and that the same type of system must be used each time. The designed methods can be used for studies not only of head movements but also of movements of other segments of the human body, and can be used to compare other types of MoCap systems, depending on the requirements for a specific rehabilitation examination.

  2. Effect of Reduced Stiffness Dance Flooring on Lower Extremity Joint Angular Trajectories During a Ballet Jump.

    Science.gov (United States)

    Hackney, James; Brummel, Sara; Newman, Mary; Scott, Shannon; Reinagel, Matthew; Smith, Jennifer

    2015-09-01

    We carried out a study to investigate how low stiffness flooring may help prevent overuse injuries of the lower extremity in dancers. It was hypothesized that performing a ballet jump (sauté) on a reduced stiffness dance floor would decrease maximum joint flexion angles and negative angular velocities at the hips, knees, or ankles compared to performing the same jump on a harder floor. The participants were 15 young adult female dancers (age range 18 to 28, mean = 20.89 ± 2.93 years) with at least 5 years of continuous ballet experience and without history of serious lower body injury, surgery, or recent pain. They performed sautés on a (low stiffness) Harlequin ® WoodSpring Floor and on a vinyl-covered hardwood on concrete floor. Maximum joint flexion angles and negative velocities at bilateral hips, knees, and ankles were measured with the "Ariel Performance Analysis System" (APAS). Paired one-tailed t-tests yielded significant decreases in maximum knee angle (average decrease = 3.4° ± 4.2°, p = 0.026) and angular negative velocity of the ankles (average decrease = 18.7°/sec ± 27.9°/sec, p = 0.009) with low stiffness flooring. If the knee angle is less acute, then the length of the external knee flexion moment arm will also be shorter and result in a smaller external knee flexion moment, given an equal landing force. Also, high velocities of eccentric muscle contraction, which are necessary to control negative angular velocity of the ankle joint, are associated with higher risk of musculotendinous injury. Hence, our findings indicate that reduced floor stiffness may indeed help decrease the likelihood of lower extremity injuries.

  3. Angular and linear momentum of excited ferromagnets

    NARCIS (Netherlands)

    Yan, P.; Kamra, A.; Cao, Y.; Bauer, G.E.W.

    2013-01-01

    The angular momentum vector of a Heisenberg ferromagnet with isotropic exchange interaction is conserved, while under uniaxial crystalline anisotropy the projection of the total spin along the easy axis is a constant of motion. Using Noether's theorem, we prove that these conservation laws persist

  4. Angular distribution in ternary cold fission

    International Nuclear Information System (INIS)

    Delion, D.S.; J.W. Goethe Univ., Frankfurt; Sandulescu, A.; J.W. Goethe Univ., Frankfurt; Greiner, W.

    2003-01-01

    We describe the spontaneous ternary cold fission of 252 Cf, accompanied by 4 He, 10 Be and 14 C. The light cluster decays from the first resonant eigenstate in the Coulomb potential plus a harmonic oscillator potential. We have shown that the angular distribution of the emitted light particle is strongly connected with its deformation and the equatorial distance. (author)

  5. Probabilistic calculation for angular dependence collision

    International Nuclear Information System (INIS)

    Villarino, E.A.

    1990-01-01

    This collision probabilistic method is broadly used in cylindrical geometry (in one- or two-dimensions). It constitutes a powerful tool for the heterogeneous Response Method where, the coupling current is of the cosine type, that is, without angular dependence at azimuthal angle θ and proportional to μ (cosine of the θ polar angle). (Author) [es

  6. Heteromodal conceptual processing in the angular gyrus.

    Science.gov (United States)

    Bonner, Michael F; Peelle, Jonathan E; Cook, Philip A; Grossman, Murray

    2013-05-01

    Concepts bind together the features commonly associated with objects and events to form networks in long-term semantic memory. These conceptual networks are the basis of human knowledge and underlie perception, imagination, and the ability to communicate about experiences and the contents of the environment. Although it is often assumed that this distributed semantic information is integrated in higher-level heteromodal association cortices, open questions remain about the role and anatomic basis of heteromodal representations in semantic memory. Here we used combined neuroimaging evidence from functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to characterize the cortical networks underlying concept representation. Using a lexical decision task, we examined the processing of concepts in four semantic categories that varied on their sensory-motor feature associations (sight, sound, manipulation, and abstract). We found that the angular gyrus was activated across all categories regardless of their modality-specific feature associations, consistent with a heteromodal account for the angular gyrus. Exploratory analyses suggested that categories with weighted sensory-motor features additionally recruited modality-specific association cortices. Furthermore, DTI tractography identified white matter tracts connecting these regions of modality-specific functional activation with the angular gyrus. These findings are consistent with a distributed semantic network that includes a heteromodal, integrative component in the angular gyrus in combination with sensory-motor feature representations in modality-specific association cortices. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. INVESTIGATION OF ANGULAR BALL BEARING WEAR

    Directory of Open Access Journals (Sweden)

    A. L. Savchenko

    2006-01-01

    Full Text Available Wearing process of balls in an angular ball bearing has been investigated in the paper. Force affecting a separator from the side of balls is determined theoretically. Wear rate may be calculated with a formula for abrasive wear while substituting numerical parameter values of the investigated ball bearing for formula symbols.

  8. Canonical three-body angular basis

    International Nuclear Information System (INIS)

    Matveenko, A.V.

    2001-01-01

    Three-body problems are basic for the quantum mechanics of molecular, atomic, or nuclear systems. We demonstrate that their variational solution for rotational states can be greatly simplified. A special choice of coordinates (hyperspherical) and of the kinematics (body-fixed coordinate frame) allows one to choose basis functions in a form that makes the angular coupling trivial. (author)

  9. Temperature and angular momentum dependence of the ...

    Indian Academy of Sciences (India)

    Temperature and angular momentum dependence of the quadrupole deformation is studied in the middle of the sd-shell for 28Si and 27Si isotopes using the spherical shell model approach. The shell model calculations have been performed using the standard universal sd-shell (USD) interaction and the canonical ...

  10. Angular momentum gated neutron evaporation studies

    International Nuclear Information System (INIS)

    Banerjee, K.; Kundu, S.; Rana, T.K.; Bhattacharya, C.; Mukherjee, G.; Gohil, M.; Meena, J.K.; Pandey, R.; Pai, H.; Dey, A.; Biswas, M.; Mukhopadhyay, S.; Pandit, D.; Pal, S.; Banerjee, S.R.; Bhattacharya, S.; Bandhopadhyay, T.

    2010-01-01

    The inverse level density parameter k (k = A/a, where A is the mass number of the compound nucleus)is investigated as a function of angular momentum by measuring γ-ray fold gated neutron evaporation spectrum in 4 He + 115 In fusion reaction using 35 MeV 4 He ion beam from VECC K130 cyclotron

  11. Angular-momentum-bearing modes in fission

    International Nuclear Information System (INIS)

    Moretto, L.G.; Peaslee, G.F.; Wozniak, G.J.

    1989-03-01

    The angular-momentum-bearing degrees of freedom involved in the fission process are identified and their influence on experimental observables is discussed. The excitation of these modes is treated in the ''thermal'' limit, and the resulting distributions of observables are calculated. Experiments demonstrating the role of these modes are presented and discussed. 61 refs., 12 figs

  12. Angular Intermittency and Analytical QCD Predictions

    CERN Document Server

    Chekanov, S.V.

    1997-01-01

    We present a comparison of local multiplicity fluctuations in angular phase-space intervals with first-order QCD predictions. The data are based on 810k hadronic events at 91.2 GeV collected with the L3 detector at LEP during 1994.

  13. Angular momentum transfer in incomplete fusion

    Indian Academy of Sciences (India)

    Keywords. Heavy-ion reactions; incomplete fusion; isomeric cross-section ratio; 12C, 16O beams; 93Nb; 89Y targets; angular momentum. ... R Tripathi1 A Goswami1. Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India; School of Studies in Physics, Vikram University, Ujjain 456 010, India ...

  14. Temperature and angular momentum dependence of the ...

    Indian Academy of Sciences (India)

    Abstract. Temperature and angular momentum dependence of the quadrupole deformation is studied in the middle of the sd-shell for 28Si and 27Si isotopes using the spherical shell model ... Department of Physics, University of Kashmir, Srinagar 190 006, India; Inter-University Accelerator Centre, New Delhi 110 067, India ...

  15. A Novel Permanent Magnetic Angular Acceleration Sensor

    Directory of Open Access Journals (Sweden)

    Hao Zhao

    2015-07-01

    Full Text Available Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2. Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.

  16. Generation Mechanism of Linear and Angular Ball Velocity in Baseball Pitching

    Directory of Open Access Journals (Sweden)

    Sekiya Koike

    2018-02-01

    Full Text Available The purpose of this study was to quantify the functional roles of the whole-body’s joint torques including fingers’ joints in the generation of ball speed and spin during baseball fast-ball pitching motion. The dynamic contributions of joint torque term, gravitational term, and motion-dependent term (MDT consisting of centrifugal force and Coriolis force, to the generation of the ball variables were calculated using two types of models. Motion and ground reaction forces of a baseball pitcher, who was instructed to throw a fastball into the target, were measured with a motion capture system with two force platforms. The results showed (1 the MDT is the largest contributor to ball speed (e.g., about 31 m/s prior to ball release when using 16-segment model, and (2 the horizontal adduction torque of pitching-side shoulder joint plays a crucial role in generating ball speed with conversion of the MDT into other terms using a recurrence formula.

  17. Real-time dynamic simulation of angular velocity and suppression of dead zone in IFOG

    Science.gov (United States)

    Gu, Hong; Huan, Yunpeng; Wang, Ansu; Luan, Jinwen

    2015-02-01

    The mechanism of the dead zone in closed-loop IFOGs is theoretically analyzed. The digital closed-loop transfer model for fiber-optic gyroscope is modified and the electronic cross-coupling interference from the feedback channel in the output signal of the detector in the forward channel is added. Using this model, we achieve a real-time dynamic simulation for the dead zone. The simulation results are basically consistent with experiment results. Before the electronic cross-coupling has been eliminated, the dead zone of the high-precision fiber-optic gyro is about , while the medium precision fiber-optic gyro is . After modifying the modulator circuit boards, the dead zone and the noise of the IFOG are of the same order of magnitude, better than and , respectively.

  18. Soft Neurological Signs in Childhood by Measurement of Arm Movements Using Acceleration and Angular Velocity Sensors

    Directory of Open Access Journals (Sweden)

    Miki Kaneko

    2015-10-01

    Full Text Available Soft neurological signs (SNS are evident in the motor performance of children and disappear as the child grows up. Therefore SNS are used as criteria for evaluating age-appropriate development of neurological function. The aim of this study was to quantify SNS during arm movement in childhood. In this study, we focused on pronation and supination, which are arm movements included in the SNS examination. Two hundred and twenty-three typically developing children aged 4–12 years (107 boys, 116 girls and 18 adults aged 21–26 years (16 males, two females participated in the experiment. To quantify SNS during pronation and supination, we calculated several evaluation index scores: bimanual symmetry, compliance, postural stability, motor speed and mirror movement. These index scores were evaluated using data obtained from sensors attached to the participants’ hands and elbows. Each score increased as age increased. Results obtained using our system showed developmental changes that were consistent with criteria for SNS. We were able to successfully quantify SNS during pronation and supination. These results indicate that it may be possible to use our system as quantitative criteria for evaluating development of neurological function.

  19. Soft neurological signs in childhood by measurement of arm movements using acceleration and angular velocity sensors.

    Science.gov (United States)

    Kaneko, Miki; Yamashita, Yushiro; Inomoto, Osamu; Iramina, Keiji

    2015-10-12

    Soft neurological signs (SNS) are evident in the motor performance of children and disappear as the child grows up. Therefore SNS are used as criteria for evaluating age-appropriate development of neurological function. The aim of this study was to quantify SNS during arm movement in childhood. In this study, we focused on pronation and supination, which are arm movements included in the SNS examination. Two hundred and twenty-three typically developing children aged 4-12 years (107 boys, 116 girls) and 18 adults aged 21-26 years (16 males, two females) participated in the experiment. To quantify SNS during pronation and supination, we calculated several evaluation index scores: bimanual symmetry, compliance, postural stability, motor speed and mirror movement. These index scores were evaluated using data obtained from sensors attached to the participants' hands and elbows. Each score increased as age increased. Results obtained using our system showed developmental changes that were consistent with criteria for SNS. We were able to successfully quantify SNS during pronation and supination. These results indicate that it may be possible to use our system as quantitative criteria for evaluating development of neurological function.

  20. The critical ionization velocity

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1980-06-01

    The critical ionization velocity effect was first proposed in the context of space plasmas. This effect occurs for a neutral gas moving through a magnetized plasma and leads to rapid ionization and braking of the relative motion when a marginal velocity, 'the critical velocity', is exceeded. Laboratory experiments have clearly established the significance of the critical velocity and have provided evidence for an underlying mechanism which relies on the combined action of electron impact ionization and a collective plasma interaction heating electrons. There is experimental support for such a mechanism based on the heating of electrons by the modified two-stream instability as part of a feedback process. Several applications to space plasmas have been proposed and the possibility of space experiments has been discussed. (author)

  1. Antarctic Ice Velocity Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of recent ice velocity data of the Antarctic ice sheet is intended for use by the polar scientific community. The data are presented in tabular form...

  2. High Velocity Gas Gun

    Science.gov (United States)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  3. Development of Angular Motion, Angular Momentum, and Torque Knowledge Bases for an Intelligent Physics Tutoring System

    National Research Council Canada - National Science Library

    Eason, Michael

    1998-01-01

    .... The knowledge base developed in this project provides the physics backbone for the rest of the tutoring system by generating the necessary equations and solution graphs to solve selected angular motion...

  4. Multichannel system for angular distribution measurements

    International Nuclear Information System (INIS)

    Burjan, V.; Kroha, V.; Putz, K.

    A description is given of the individual blocks of the spectrometric apparatus used for measuring the angular distribution of particle spectra and excitation functions of (d,p) reactions at an electrostatic accelerator and the U-120 M cyclotron, both operating at the Nuclear Physics Institute of the Czechoslovak Academy of Sciences at Rez. Main attention was devoted to attaining maximum energy resolution at a high measurement efficiency, this by installing 8 independent spectrometric chains allowing simultaneous measurement of angular distribution in 8 points of the beam. The semiconductor detectors were cooled to -40 degC to -60 degC, which significantly reduced the level of inherent detector noise. An energy resolution of 13 keV was attained using Tesla detectors at a particle energy of 11 MeV. A brief review of data processing and software is given. (B.S.)

  5. Coherent Control of Photoelectron Wavepacket Angular Interferograms

    OpenAIRE

    Hockett, Paul; Wollenhaupt, Matthias; Baumert, Thomas

    2015-01-01

    Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the cohere...

  6. Angular distribution of laser ablation plasma

    International Nuclear Information System (INIS)

    Kondo, K.; Kanesue, T.; Dabrowski, R.; Okamura, M.

    2010-01-01

    An expansion of a laser induced plasma is fundamental and important phenomena in a laser ion source. To understand the expanding direction, an array of Langmuir probes were employed. The chosen ion for the experiment was Ag 1+ which was created by a second harmonics of a Nd-YAG laser. The obtained angular distribution was about ±10 degree. This result also indicates a proper positioning of a solenoid magnet which enhances ion beam current.

  7. Continuum angular distributions in the transition regions

    International Nuclear Information System (INIS)

    Kalbach, C.

    1993-01-01

    One of the open questions from the 1988 published systematics of continuum angular distributions in light particle reactions is addressed. Evidence for a smooth transition in the systematics at incident energies of ∼125 MeV is summarized, and appropriate revisions to the global parameterization are proposed. Applying similar changes to the second-order term helps to remove problems noted in the literature with low-energy (N,α) reactions

  8. Coincident-inclusive electrofission angular correlations

    International Nuclear Information System (INIS)

    Arruda Neto, J.D.T.

    1983-08-01

    A method for the joint analysis of coincident and inclusive electrofission data, in order to minimize effects of the model dependence of data interpretation, is developed. Explicit calculations of the (e,e'f) angular correlations are presented. The potentialities of the method to the study of sub- and near-barrier properties of the fission process, and to the study of the giant resonances fission mode, are discussed. (Author) [pt

  9. Spatial angular compounding of photoacoustic images

    OpenAIRE

    Kang, Hyun Jae; Bell, Muyinatu A Lediju; Guo, Xiaoyu; Boctor, Emad M.

    2016-01-01

    Photoacoustic (PA) images utilize pulsed lasers and ultrasound transducers to visualize targets with higher optical absorption than the surrounding medium. However, they are susceptible to acoustic clutter and background noise artifacts that obfuscate biomedical structures of interest. We investigated three spatial-angular compounding methods to improve PA image quality for biomedical applications, implemented by combining multiple images acquired as an ultrasound probe was rotated about the ...

  10. Orbital angular momentum light in microscopy.

    Science.gov (United States)

    Ritsch-Marte, Monika

    2017-02-28

    Light with a helical phase has had an impact on optical imaging, pushing the limits of resolution or sensitivity. Here, special emphasis will be given to classical light microscopy of phase samples and to Fourier filtering techniques with a helical phase profile, such as the spiral phase contrast technique in its many variants and areas of application.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

  11. Continuous particle spectra and their angular distributions

    International Nuclear Information System (INIS)

    Sastry, Ch.V.; Jain, R.K.; Rama Rao, J.; Ernst, J.; Machner, H.

    1996-01-01

    The angular distribution of continuous particle spectra in pre-equilibrium reactions is still an unsolved problem, particularly so at forward angles. In the present work, the angular distributions of alpha particles emitted in (α, α',x) reactions in the target elements gold and rhodium have been studied in detail. Alpha particle beams of energy 60 MeV from the Variable Energy Cyclotron of Calcutta were used in these experiments. The theoretical calculations were done using an extended exciton model of Kalbach incorporated into the Computer Code PRECO-D2. The formalism used in the exciton model was modified to include division of pre equilibrium cross section into multi-step direct (MSD) and multi-step compound (MSC) components. These MSD and MSC cross sections were used to calculate the angular distributions in terms of Legendre polynomials whose coefficients are given by simple phenomenological relations. Even with a reasonable set of parameters, the agreement between theory and experiment was far from satisfactory at forward angles. Similar conclusion was also drawn in the case of continuous particle spectra of deuterons in (d, d'x) reactions at 25 MeV in various targets. (author). 10 refs., 2 figs

  12. The Cosmology Large Angular Scale Surveyor

    Science.gov (United States)

    Harrington, Kathleen; Marriage, Tobias; Ali, Aamir; Appel, John; Bennett, Charles; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; hide

    2016-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from inflation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).

  13. The Cosmology Large Angular Scale Surveyor (CLASS)

    Science.gov (United States)

    Harrington, Kathleen; Marriange, Tobias; Aamir, Ali; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; hide

    2016-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).

  14. Verification of angular dependence in MOSFET detector

    International Nuclear Information System (INIS)

    Souza, Clayton H.; Shorto, Julian M.B.; Siqueira, Paulo T.D.; Nunes, Maíra G.; Silva Junior, Iremar A.; Yoriyaz, Hélio

    2017-01-01

    In vivo dosimetry is an essential tool for quality assurance programs, being a procedure commonly performed with thermoluminescent dosimeters (TLDs) or diodes. However, a type of dosimeter that has increasing popularity in recent years is the metal-oxide-semiconductor field effect transistor (MOSFET) detector. MOSFET dosimeters fulfill all the necessary characteristics to realize in vivo dosimetry since it has a small size, good precision and feasibility of measurement, as well as easy handling. Nevertheless, its true differential is to allow reading of the dose in real time, enabling immediate intervention in the correction of physical parameters deviations and anticipation of small anatomical changes in a patient during treatment. In order for MOSFET dosimeter to be better accepted in clinical routine, information reporting performance should be available frequently. For this reason, this work proposes to verify reproducibility and angular dependence of a standard sensitivity MOSFET dosimeter (TN-502RD-H) for Cs-137 and Co-60 sources. Experimental data were satisfactory and MOSFET dosimeter presented a reproducibility of 3.3% and 2.7% (1 SD) for Cs-137 and Co-60 sources, respectively. In addition, an angular dependence of up to 6.1% and 16.3% for both radioactive sources, respectively. It is conclusive that MOSFET dosimeter TN-502RD-H has satisfactory reproducibility and a considerable angular dependence, mainly for the Co-60 source. This means that although precise measurements, special attention must be taken for applications in certain anatomical regions in a patient. (author)

  15. Angular craniometry in craniocervical junction malformation.

    Science.gov (United States)

    Botelho, Ricardo Vieira; Ferreira, Edson Dener Zandonadi

    2013-10-01

    The craniometric linear dimensions of the posterior fossa have been relatively well studied, but angular craniometry has been poorly studied and may reveal differences in the several types of craniocervical junction malformation. The objectives of this study were to evaluate craniometric angles compared with normal subjects and elucidate the main angular differences among the types of craniocervical junction malformation and the correlation between craniocervical and cervical angles. Angular craniometries were studied using primary cranial angles (basal and Boogard's) and secondary craniocervical angles (clivus canal and cervical spine lordosis). Patients with basilar invagination had significantly wider basal angles, sharper clivus canal angles, larger Boogard's angles, and greater cervical lordosis than the Chiari malformation and control groups. The Chiari malformation group does not show significant differences when compared with normal controls. Platybasia occurred only in basilar invagination and is suggested to be more prevalent in type II than in type I. Platybasic patients have a more acute clivus canal angle and show greater cervical lordosis than non-platybasics. The Chiari group does not show significant differences when compared with the control, but the basilar invagination groups had craniometric variables significantly different from normal controls. Hyperlordosis observed in the basilar inavagination group was associated with craniocervical kyphosis conditioned by acute clivus canal angles.

  16. Verification of angular dependence in MOSFET detector

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Clayton H.; Shorto, Julian M.B.; Siqueira, Paulo T.D.; Nunes, Maíra G.; Silva Junior, Iremar A.; Yoriyaz, Hélio, E-mail: chsouza@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-07-01

    In vivo dosimetry is an essential tool for quality assurance programs, being a procedure commonly performed with thermoluminescent dosimeters (TLDs) or diodes. However, a type of dosimeter that has increasing popularity in recent years is the metal-oxide-semiconductor field effect transistor (MOSFET) detector. MOSFET dosimeters fulfill all the necessary characteristics to realize in vivo dosimetry since it has a small size, good precision and feasibility of measurement, as well as easy handling. Nevertheless, its true differential is to allow reading of the dose in real time, enabling immediate intervention in the correction of physical parameters deviations and anticipation of small anatomical changes in a patient during treatment. In order for MOSFET dosimeter to be better accepted in clinical routine, information reporting performance should be available frequently. For this reason, this work proposes to verify reproducibility and angular dependence of a standard sensitivity MOSFET dosimeter (TN-502RD-H) for Cs-137 and Co-60 sources. Experimental data were satisfactory and MOSFET dosimeter presented a reproducibility of 3.3% and 2.7% (1 SD) for Cs-137 and Co-60 sources, respectively. In addition, an angular dependence of up to 6.1% and 16.3% for both radioactive sources, respectively. It is conclusive that MOSFET dosimeter TN-502RD-H has satisfactory reproducibility and a considerable angular dependence, mainly for the Co-60 source. This means that although precise measurements, special attention must be taken for applications in certain anatomical regions in a patient. (author)

  17. Revolution evolution: tracing angular momentum during star and planetary system formation

    Science.gov (United States)

    Davies, Claire Louise

    2015-04-01

    Stars form via the gravitational collapse of molecular clouds during which time the protostellar object contracts by over seven orders of magnitude. If all the angular momentum present in the natal cloud was conserved during collapse, stars would approach rotational velocities rapid enough to tear themselves apart within just a few Myr. In contrast to this, observations of pre-main sequence rotation rates are relatively slow (∼ 1 - 15 days) indicating that significant quantities of angular momentum must be removed from the star. I use observations of fully convective pre-main sequence stars in two well-studied, nearby regions of star formation (namely the Orion Nebula Cluster and Taurus-Auriga) to determine the removal rate of stellar angular momentum. I find the accretion disc-hosting stars to be rotating at a slower rate and contain less specific angular momentum than the disc-less stars. I interpret this as indicating a period of accretion disc-regulated angular momentum evolution followed by near-constant rotational evolution following disc dispersal. Furthermore, assuming that the age spread inferred from the Hertzsprung-Russell diagram constructed for the star forming region is real, I find that the removal rate of angular momentum during the accretion-disc hosting phase to be more rapid than that expected from simple disc-locking theory whereby contraction occurs at a fixed rotation period. This indicates a more efficient process of angular momentum removal must operate, most likely in the form of an accretion-driven stellar wind or outflow emanating from the star-disc interaction. The initial circumstellar envelope that surrounds a protostellar object during the earliest stages of star formation is rotationally flattened into a disc as the star contracts. An effective viscosity, present within the disc, enables the disc to evolve: mass accretes inwards through the disc and onto the star while momentum migrates outwards, forcing the outer regions of the

  18. Constraints on radial migration in spiral galaxies - II. Angular momentum distribution and preferential migration

    Science.gov (United States)

    Daniel, Kathryne J.; Wyse, Rosemary F. G.

    2018-05-01

    The orbital angular momentum of individual stars in galactic discs can be permanently changed through torques from transient spiral patterns. Interactions at the corotation resonance dominate these changes and have the further property of conserving orbital circularity. We derived in an earlier paper an analytic criterion that an unperturbed stellar orbit must satisfy in order for such an interaction to occur, i.e. for it to be in a trapped orbit around corotation. We here use this criterion in an investigation of how the efficiency of induced radial migration for a population of disc stars varies with the angular momentum distribution of that population. We frame our results in terms of the velocity dispersion of the population, this being an easier observable than is the angular momentum distribution. Specifically, we investigate how the fraction of stars in trapped orbits at corotation varies with the velocity dispersion of the population, for a system with an assumed flat rotation curve. Our analytic results agree with the finding from simulations that radial migration is less effective in populations with `hotter' kinematics. We further quantify the dependence of this trapped fraction on the strength of the spiral pattern, finding a higher trapped fraction for higher amplitude perturbations.

  19. Angular dispersion and energy loss of H+ and He+ in metals

    International Nuclear Information System (INIS)

    Cantero, Esteban

    2006-01-01

    In this master thesis the effects produced when a light ion beam traverses a thin metallic film were studied.In particular, the interactions of low energy (E ≤ 10 keV) light ions (H + ,H 2 + , D + , He + ) with monocrystalline and also polycrystalline gold samples were investigated.In first place, the dependence of the stopping power with projectiles' velocity was studied, analyzing the threshold effect in the excitation of the 5d electrons in the channelling regime for energies between 0,4 and 9 keV.Next, the angular dispersion of ions in polycrystalline and monocrystalline films was measured and analyzed.Comparisons for different energies and projectiles were done, studying molecular and isotopic effects.Using Lindhard's channeling theory, a scale law for the angular dispersion of angles greater than the critical angle was found.Additionally, the angular dependence of the energy loss and the energy loss straggling of protons transmitted through monocrystals were measured.To explain the angular variations of these magnitudes a theoretical model based on the electronic density fluctuations inside the channel was developed [es

  20. A novel methodology for the angular position identification of the unbalance force on asymmetric rotors by response polar plot analysis

    Science.gov (United States)

    Colín Ocampo, Jorge; Gutiérrez Wing, Enrique S.; Ramírez Moroyoqui, Félix J.; Abúndez Pliego, Arturo; Blanco Ortega, Andrés; Mayén, Jan

    2017-10-01

    It is well known that some mechanical systems, as a two pole generator, exhibit two different stiffness on the main inertial axis of its transverse section, which leads to complex vibration modes and complicates the determination of the angular position of the unbalance force and, consequently, the balancing process by conventional methods. Therefore, a methodology for the angular position identification of the unbalance force, based on a two-degrees-of-freedom mathematical simplified model of a rotor with unequal principal moments of inertia of the shaft transverse section, is proposed in this work. The methodology requires the analysis of the response polar plots of the rotor, as well as the information of the vibration response of at least four points from the response polar plot: vibration amplitude, phase angle and the angular velocity of the rotor. The identification of the unbalance force angular position was numerically and experimentally validated using the response polar plots experimentally acquired from a Jeffcott type rotor, which exhibits unequal principal moments of inertia of shaft transverse section and two inertial disks, which were analyzed for several unbalance force angular positions. The results showed slight differences between the identified and the experimental angular positions.

  1. Velocity pump reaction turbine

    Science.gov (United States)

    House, P.A.

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  2. The Prescribed Velocity Method

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm

    The- velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactory...... description of this momentum flow. The Prescribed Velocity Method is a practical method for the description of an Air Terminal Device which will save grid points close to the opening and ensure the right level of the momentum flow....

  3. Coding of Velocity Storage in the Vestibular Nuclei

    Directory of Open Access Journals (Sweden)

    Sergei B. Yakushin

    2017-08-01

    Full Text Available Semicircular canal afferents sense angular acceleration and output angular velocity with a short time constant of ≈4.5 s. This output is prolonged by a central integrative network, velocity storage that lengthens the time constants of eye velocity. This mechanism utilizes canal, otolith, and visual (optokinetic information to align the axis of eye velocity toward the spatial vertical when head orientation is off-vertical axis. Previous studies indicated that vestibular-only (VO and vestibular-pause-saccade (VPS neurons located in the medial and superior vestibular nucleus could code all aspects of velocity storage. A recently developed technique enabled prolonged recording while animals were rotated and received optokinetic stimulation about a spatial vertical axis while upright, side-down, prone, and supine. Firing rates of 33 VO and 8 VPS neurons were studied in alert cynomolgus monkeys. Majority VO neurons were closely correlated with the horizontal component of velocity storage in head coordinates, regardless of head orientation in space. Approximately, half of all tested neurons (46% code horizontal component of velocity in head coordinates, while the other half (54% changed their firing rates as the head was oriented relative to the spatial vertical, coding the horizontal component of eye velocity in spatial coordinates. Some VO neurons only coded the cross-coupled pitch or roll components that move the axis of eye rotation toward the spatial vertical. Sixty-five percent of these VO and VPS neurons were more sensitive to rotation in one direction (predominantly contralateral, providing directional orientation for the subset of VO neurons on either side of the brainstem. This indicates that the three-dimensional velocity storage integrator is composed of directional subsets of neurons that are likely to be the bases for the spatial characteristics of velocity storage. Most VPS neurons ceased firing during drowsiness, but the firing

  4. Eccentricity samples: Implications on the potential and the velocity distribution

    Directory of Open Access Journals (Sweden)

    Cubarsi R.

    2017-01-01

    Full Text Available Planar and vertical epicycle frequencies and local angular velocity are related to the derivatives up to the second order of the local potential and can be used to test the shape of the potential from stellar disc samples. These samples show a more complex velocity distribution than halo stars and should provide a more realistic test. We assume an axisymmetric potential allowing a mixture of independent ellipsoidal velocity distributions, of separable or Staeckel form in cylindrical or spherical coordinates. We prove that values of local constants are not consistent with a potential separable in addition in cylindrical coordinates and with a spherically symmetric potential. The simplest potential that fits the local constants is used to show that the harmonical and non-harmonical terms of the potential are equally important. The same analysis is used to estimate the local constants. Two families of nested subsamples selected for decreasing planar and vertical eccentricities are used to borne out the relation between the mean squared planar and vertical eccentricities and the velocity dispersions of the subsamples. According to the first-order epicycle model, the radial and vertical velocity components provide accurate information on the planar and vertical epicycle frequencies. However, it is impossible to account for the asymmetric drift which introduces a systematic bias in estimation of the third constant. Under a more general model, when the asymmetric drift is taken into account, the rotation velocity dispersions together with their asymmetric drift provide the correct fit for the local angular velocity. The consistency of the results shows that this new method based on the distribution of eccentricities is worth using for kinematic stellar samples. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. No 176011: Dynamics and Kinematics of Celestial Bodies and Systems

  5. Robust finite-time tracking control of nonholonomic mobile robots without velocity measurements

    Science.gov (United States)

    Shi, Shang; Yu, Xin; Khoo, Suiyang

    2016-02-01

    The problem of robust finite-time trajectory tracking of nonholonomic mobile robots with unmeasurable velocities is studied. The contributions of the paper are that: first, in the case that the angular velocity of the mobile robot is unmeasurable, a composite controller including the observer-based partial state feedback control and the disturbance feed-forward compensation is designed, which guarantees that the tracking errors converge to zero in finite time. Second, if the linear velocity as well as the angular velocity of mobile robot is unmeasurable, with a stronger constraint, the finite-time trajectory tracking control of nonholonomic mobile robot is also addressed. Finally, the effectiveness of the proposed control laws is demonstrated by simulation.

  6. Angular-Momentum Evolution in Laser-Plasma Accelerators

    CERN Document Server

    Thaury, Cédric; Corde, Sébastien; Lehe, Rémi; Le Bouteiller, Madeleine; Ta Phuoc, Kim; Davoine, Xavier; Rax, J. M.; Rousse, Antoine; Malka, Victor

    2013-01-01

    The transverse properties of an electron beam are characterized by two quantities, the emittance which indicates the electron beam extent in the phase space and the angular momentum which allows for non-planar electron trajectories. Whereas the emittance of electron beams produced in laserplasma accelerator has been measured in several experiments, their angular momentum has been scarcely studied. It was demonstrated that electrons in laser-plasma accelerator carry some angular momentum, but its origin was not established. Here we identify one source of angular momentum growth and we present experimental results showing that the angular momentum content evolves during the acceleration.

  7. Research on static angular stiffness measurement of flexible joint

    Directory of Open Access Journals (Sweden)

    Yongchao HUANG

    2016-10-01

    Full Text Available Measurement accuracy of the angular stiffness of flexible joint is directly related to the control accuracy and sensitivity of gyro, but the traditional measurement methods have many problems. According to the principle of angular stiffness measurement of flexible joint, two static measurement methods of angular stiffness are proposed based on different loading ways, namely mechanical loading angular stiffness measurement and piezoelectric loading angular stiffness measurement. The mechanical loading angular stiffness measurement system is built by using a motor driven indexing feeding tilting table, the measure experiment if the angular stiffness of flexible joint is conducted, and the angular stiffness of flexible joint is measured. For the excessive fluctuation problem of the measure result in mechanical load test, a piezoelectric loading structure is designed and a measurement method employing piezoelectric actuator is proposed for angular stiffness measurement of flexible joint. Based on ANSYS Workbench, the displacement output of the piezoelectric loading structure is analyzed by simulations. The simulation results illustrate that the displacement output meets the requirement of static loading angular stiffness measurement of flexible joint, and the theoretical feasibility of piezoelectric loading angular stiffness measurement method is validated.

  8. Negative refraction angular characterization in one-dimensional photonic crystals.

    Directory of Open Access Journals (Sweden)

    Jesus Eduardo Lugo

    2011-04-01

    Full Text Available Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity developed here. We also analytically derived the negative refraction correctness condition that gives the angular region where negative refraction occurs.By using standard photonic techniques we experimentally determined the relationship between incidence and negative refraction angles and found the negative refraction range by applying the correctness condition. In order to compare both theories with experimental results an output refraction correction was utilized. The correction uses Snell's law and an effective refractive index based on two effective dielectric constants. We found good agreement between experiment and both theories in the negative refraction zone.Since both theories and the experimental observations agreed well in the negative refraction region, we can use both negative refraction theories plus the output correction to predict negative refraction angles. This can be very useful from a practical point of view for space filtering applications such as a photonic demultiplexer or for sensing applications.

  9. Angular Rate Estimation Using a Distributed Set of Accelerometers

    Directory of Open Access Journals (Sweden)

    Sung Kyung Hong

    2011-11-01

    Full Text Available A distributed set of accelerometers based on the minimum number of 12 accelerometers allows for computation of the magnitude of angular rate without using the integration operation. However, it is not easy to extract the magnitude of angular rate in the presence of the accelerometer noises, and even worse, it is difficult to determine the direction of a rotation because the angular rate is present in its quadratic form within the inertial measurement system equations. In this paper, an extended Kalman filter scheme to correctly estimate both the direction and magnitude of the angular rate through fusion of the angular acceleration and quadratic form of the angular rate is proposed. We also provide observability analysis for the general distributed accelerometers-based inertial measurement unit, and show that the angular rate can be correctly estimated by general nonlinear state estimators such as an extended Kalman filter, except under certain extreme conditions.

  10. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  11. Generalized extended Navier-Stokes theory: correlations in molecular fluids with intrinsic angular momentum.

    Science.gov (United States)

    Hansen, J S; Daivis, Peter J; Dyre, Jeppe C; Todd, B D; Bruus, Henrik

    2013-01-21

    The extended Navier-Stokes theory accounts for the coupling between the translational and rotational molecular degrees of freedom. In this paper, we generalize this theory to non-zero frequencies and wavevectors, which enables a new study of spatio-temporal correlation phenomena present in molecular fluids. To discuss these phenomena in detail, molecular dynamics simulations of molecular chlorine are performed for three different state points. In general, the theory captures the behavior for small wavevector and frequencies as expected. For example, in the hydrodynamic regime and for molecular fluids with small moment of inertia like chlorine, the theory predicts that the longitudinal and transverse intrinsic angular velocity correlation functions are almost identical, which is also seen in the molecular dynamics simulations. However, the theory fails at large wavevector and frequencies. To account for the correlations at these scales, we derive a phenomenological expression for the frequency dependent rotational viscosity and wavevector and frequency dependent longitudinal spin viscosity. From this we observe a significant coupling enhancement between the molecular angular velocity and translational velocity for large frequencies in the gas phase; this is not observed for the supercritical fluid and liquid state points.

  12. Angular Position Tracking Control of a Quadcopter

    OpenAIRE

    T. V. Glazkov; A. E. Golubev

    2017-01-01

    The paper dwells on tracking the quad-copter angular position with desired quality parameters of transient processes. The aerial vehicle is considered as a rigid body with six degrees of freedom.  A full rigid body quad-copter mathematical model is considered without the assumption of smallness of the Euler angles.Among the most well known methods of non-linear stabilization are feedback linearization and backstepping. The backstepping approach allows us to have an effective solution of the s...

  13. Angular Momentum Sensitive Two-Center Interference

    Science.gov (United States)

    Ilchen, M.; Glaser, L.; Scholz, F.; Walter, P.; Deinert, S.; Rothkirch, A.; Seltmann, J.; Viefhaus, J.; Decleva, P.; Langer, B.; Knie, A.; Ehresmann, A.; Al-Dossary, O. M.; Braune, M.; Hartmann, G.; Meissner, A.; Tribedi, L. C.; AlKhaldi, M.; Becker, U.

    2014-01-01

    In quantum mechanics the Young-type double-slit experiment can be performed with electrons either traveling through a double slit or being coherently emitted from two inversion symmetric molecular sites. In the latter one the valence photoionization cross sections of homonuclear diatomic molecules were predicted to oscillate over kinetic energy almost 50 years ago. Beyond the direct proof of the oscillatory behavior of these photoionization cross sections σ, we show that the angular distribution of the emitted electrons reveals hitherto unexplored information on the relative phase shift between the corresponding partial waves through two-center interference patterns.

  14. Projection of angular momentum via linear algebra

    Science.gov (United States)

    Johnson, Calvin W.; O'Mara, Kevin D.

    2017-12-01

    Projection of many-body states with good angular momentum from an initial state is usually accomplished by a three-dimensional integral. We show how projection can instead be done by solving a straightforward system of linear equations. We demonstrate the method and give sample applications to 48Cr and 60Fe in the p f shell. This new projection scheme, which is competitive against the standard numerical quadrature, should also be applicable to other quantum numbers such as isospin and particle number.

  15. The angular momentum of isolated white dwarfs

    Directory of Open Access Journals (Sweden)

    Brassard P.

    2013-03-01

    Full Text Available This is a very brief report on an ongoing program aimed at mapping the internal rotation profiles of stars through asteroseismology. Three years ago, we developed and applied successfully a new technique to the pulsating GW Vir white dwarf PG 1159−035, and were able to infer that it rotates very slowly and rigidly over some 99% of its mass. We applied the same approach to the three other GW Vir pulsators with available rotational splitting data, and found similar results. We discuss the implications of these findings on the question of the angular momentum of white dwarfs resulting from single star evolution.

  16. Models and theory for precompound angular distributions

    Energy Technology Data Exchange (ETDEWEB)

    Blann, M.; Pohl, B.A.; Remington, B.A. (Lawrence Livermore National Lab., CA (USA)); Scobel, W.; Trabandt, M. (Hamburg Univ. (Germany, F.R.). 1. Inst. fuer Experimentalphysik); Byrd, R.C. (Los Alamos National Lab., NM (USA)); Foster, C.C. (Indiana Univ. Cyclotron Facility, Bloomington, IN (USA)); Bonetti, R.; Chiesa, C. (Milan Univ. (Italy). Ist. di Fisica Generale Applicata); Grimes, S.M. (Ohio Univ

    1990-06-06

    We compare angular distributions calculated by folding nucleon- nucleon scattering kernels, using the theory of Feshbach, Kerman and Koonin, and the systematics of Kalbach, with a wide range of data. The data range from (n,xn) at 14 MeV incident energy to (p,xn) at 160 MeV incident energy. The FKK theory works well with one adjustable parameter, the depth of the nucleon-nucleon interaction potential. The systematics work well when normalized to the hybrid model single differential cross section prediction. The nucleon- nucleon scattering approach seems inadequate. 9 refs., 10 figs.

  17. Influence of tungsten fiber’s slow drift on the measurement of G with angular acceleration method

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jie; Wu, Wei-Huang; Zhan, Wen-Ze [School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074 (China); Xue, Chao [MOE Key Laboratory of Fundamental Physical Quantities Measurement, School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics and Astronomy, Sun Yat-sen University, Guangzhou 510275 (China); Shao, Cheng-Gang, E-mail: cgshao@mail.hust.edu.cn; Wu, Jun-Fei [MOE Key Laboratory of Fundamental Physical Quantities Measurement, School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Milyukov, Vadim [Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow 119992 (Russian Federation)

    2016-08-15

    In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value of G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.

  18. Young-type interference effect on angular distribution of secondary electrons emitted from H2 in collisions with fast electrons

    Science.gov (United States)

    Chatterjee, Shyamal; Misra, D.; Kelkar, A. H.; Tribedi, Lokesh C.; Stia, C. R.; Fojón, O. A.; Rivarola, R. D.

    2008-11-01

    The Young-type interference arising due to the spatial coherence has been investigated in the electron emission spectrum from fast electron impact ionization of the inversion symmetric homonuclear diatomic molecule H2 . The evidence of the interference effect in the angular distribution of the double differential spectrum of the secondary electron is found. The signature of constructive interferences has been identified in the soft-collision regions as well as in binary encounters. The observed oscillation in the forward-backward asymmetry parameter is explained in terms of the Cohen-Fano-type interference coupled with the angular dependence of oscillation frequency. A comparative study indicates a marked difference between the angular asymmetry in the case of fast heavy ion (F9+) and electron collisions with H2 at a similar velocity.

  19. Importance of energy and angular resolutions in top-hat electrostatic analysers for solar wind proton measurements

    Science.gov (United States)

    De Marco, R.; Marcucci, M. F.; Bruno, R.; D'Amicis, R.; Servidio, S.; Valentini, F.; Lavraud, B.; Louarn, P.; Salatti, M.

    2016-08-01

    We use a numerical code which reproduces the angular/energy response of a typical top-hat electrostatic analyser starting from solar wind proton velocity distribution functions (VDFs) generated by numerical simulations. The simulations are based on the Hybrid Vlasov-Maxwell numerical algorithm which integrates the Vlasov equation for the ion distribution function, while the electrons are treated as a fluid. A virtual satellite launched through the simulation box measures the particle VDFs. Such VDFs are moved from the simulation Cartesian grid to energy-angular coordinates to mimic the response of a real sensor in the solar wind. Different energy-angular resolutions of the analyser are investigated in order to understand the influence of the phase-space resolution in existing and upcoming space missions, with regards to determining the key parameters of plasma dynamics.

  20. A proposed measurement of optical orbital and spin angular momentum and its implications for photon angular momentum

    Science.gov (United States)

    Leader, Elliot

    2018-04-01

    The expression for the total angular momentum carried by a laser optical vortex beam, splits, in the paraxial approximation, into two terms which seem to represent orbital and spin angular momentum respectively. There are, however, two very different competing versions of the formula for the spin angular momentum, one based on the use of the Poynting vector, as in classical electrodynamics, the other related to the canonical expression for the angular momentum which occurs in Quantum Electrodynamics. I analyze the possibility that a sufficiently sensitive optical measurement could decide which of these corresponds to the actual physical angular momentum carried by the beam.

  1. Sensor Data Quality and Angular Rate Down-Selection Algorithms on SLS EM-1

    Science.gov (United States)

    Park, Thomas; Smith, Austin; Oliver, T. Emerson

    2018-01-01

    The NASA Space Launch System Block 1 launch vehicle is equipped with an Inertial Navigation System (INS) and multiple Rate Gyro Assemblies (RGA) that are used in the Guidance, Navigation, and Control (GN&C) algorithms. The INS provides the inertial position, velocity, and attitude of the vehicle along with both angular rate and specific force measurements. Additionally, multiple sets of co-located rate gyros supply angular rate data. The collection of angular rate data, taken along the launch vehicle, is used to separate out vehicle motion from flexible body dynamics. Since the system architecture uses redundant sensors, the capability was developed to evaluate the health (or validity) of the independent measurements. A suite of Sensor Data Quality (SDQ) algorithms is responsible for assessing the angular rate data from the redundant sensors. When failures are detected, SDQ will take the appropriate action and disqualify or remove faulted sensors from forward processing. Additionally, the SDQ algorithms contain logic for down-selecting the angular rate data used by the GNC software from the set of healthy measurements. This paper explores the trades and analyses that were performed in selecting a set of robust fault-detection algorithms included in the GN&C flight software. These trades included both an assessment of hardware-provided health and status data as well as an evaluation of different algorithms based on time-to-detection, type of failures detected, and probability of detecting false positives. We then provide an overview of the algorithms used for both fault-detection and measurement down selection. We next discuss the role of trajectory design, flexible-body models, and vehicle response to off-nominal conditions in setting the detection thresholds. Lastly, we present lessons learned from software integration and hardware-in-the-loop testing.

  2. Transverse Spectral Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    array probe is used along with two different estimators based on the correlation of the received signal. They can estimate the velocity spectrum as a function of time as for ordinary spectrograms, but they also work at a beam-to-flow angle of 90°. The approach is validated using simulations of pulsatile...... flow using the Womersly–Evans flow model. The relative bias of the mean estimated frequency is 13.6% and the mean relative standard deviation is 14.3% at 90°, where a traditional estimator yields zero velocity. Measurements have been conducted with an experimental scanner and a convex array transducer....... A pump generated artificial femoral and carotid artery flow in the phantom. The estimated spectra degrade when the angle is different from 90°, but are usable down to 60° to 70°. Below this angle the traditional spectrum is best and should be used. The conventional approach can automatically be corrected...

  3. The Cosmology Large Angular Scale Surveyor (CLASS)

    Science.gov (United States)

    Cleary, Joseph

    2018-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is an array of four telescopes designed to measure the polarization of the Cosmic Microwave Background. CLASS aims to detect the B-mode polarization from primordial gravitational waves predicted by cosmic inflation theory, as well as the imprint left by reionization upon the CMB E-mode polarization. This will be achieved through a combination of observing strategy and state-of-the-art instrumentation. CLASS is observing 70% of the sky to characterize the CMB at large angular scales, which will measure the entire CMB power spectrum from the reionization peak to the recombination peak. The four telescopes operate at frequencies of 38, 93, 145, and 217 GHz, in order to estimate Galactic synchrotron and dust foregrounds while avoiding atmospheric absorption. CLASS employs rapid polarization modulation to overcome atmospheric and instrumental noise. Polarization sensitive cryogenic detectors with low noise levels provide CLASS the sensitivity required to constrain the tensor-to-scalar ratio down to levels of r ~ 0.01 while also measuring the optical depth the reionization to sample-variance levels. These improved constraints on the optical depth to reionization are required to pin down the mass of neutrinos from complementary cosmological data. CLASS has completed a year of observations at 38 GHz and is in the process of deploying the rest of the telescope array. This poster provides an overview and update on the CLASS science, hardware and survey operations.

  4. Practical scaling law for photoelectron angular distributions

    International Nuclear Information System (INIS)

    Guo Dongsheng; Zhang Jingtao; Xu Zhizhan; Li Xiaofeng; Fu Panming; Freeman, R.R.

    2003-01-01

    A practical scaling law that predicts photoelectron angular distributions (PADs) is derived using angular distribution formulas which explicitly contain spontaneous emission. The scaling law is used to analyze recent PAD measurements in above-threshold ionization, and to predict results of future experiments. Our theoretical and numerical studies show that, in the non-relativistic regime and long-wavelength approximation, the shapes of PADs are determined by only three dimensionless numbers: (1) u p ≡U p /(ℎ/2π)ω, the ponderomotive number (ponderomotive energy in units of laser photon energy); (2) ε b ≡E b /(ℎ/2π)ω, the binding number (atomic binding energy in units of the laser photon energy); (3) j, the absorbed-photon number. The scaling law is shown to be useful in predictions of results from strong-field Kapitza-Dirac effect measurements; specifically, the application of this scaling law to recently reported Kapitza-Dirac diffraction is discussed. Possible experimental tests to verify the scaling law are suggested

  5. Orbital angular momentum of general astigmatic modes

    International Nuclear Information System (INIS)

    Visser, Jorrit; Nienhuis, Gerard

    2004-01-01

    We present an operator method to obtain complete sets of astigmatic Gaussian solutions of the paraxial wave equation. In case of general astigmatism, the astigmatic intensity and phase distribution of the fundamental mode differ in orientation. As a consequence, the fundamental mode has a nonzero orbital angular momentum, which is not due to phase singularities. Analogous to the operator method for the quantum harmonic oscillator, the corresponding astigmatic higher-order modes are obtained by repeated application of raising operators on the fundamental mode. The nature of the higher-order modes is characterized by a point on a sphere, in analogy with the representation of polarization on the Poincare sphere. The north and south poles represent astigmatic Laguerre-Gaussian modes, similar to circular polarization on the Poincare sphere, while astigmatic Hermite-Gaussian modes are associated with points on the equator, analogous to linear polarization. We discuss the propagation properties of the modes and their orbital angular momentum, which depends on the degree of astigmatism and on the location of the point on the sphere

  6. [Sensitivity of four representative angular cephalometric measures].

    Science.gov (United States)

    Xü, T; Ahn, J; Baumrind, S

    2000-05-01

    Examined the sensitivity of four representative cephalometric angles to the detection of different vectors of craniofacial growth. Landmark coordinate data from a stratified random sample of 48 adolescent subjects were used to calculate conventional values for changes between the pretreatment and end-of-treatment lateral cephalograms. By modifying the end-of-treatment coordinate values appropriately, the angular changes could be recalculated reflecting three hypothetical situations: Case 1. What if there were no downward landmark displacement between timepoints? Case 2. What if there were no forward landmark displacement between timepoints? Case 3. What if there were no Nasion change? These questions were asked for four representative cephalometric angles: SNA, ANB, NAPg and UI-SN. For Case 1, the associations (r) between the baseline and the modified measure for the three angles were very highly significant (P < 0.001) with r2 values no lower than 0.94! For Case 2, however, the associations were much weaker and no r value reached significance. These angular measurements are less sensitive for measuring downward landmark displacement than they are for measuring forward landmark displacement.

  7. The key kinematic determinants of undulatory underwater swimming at maximal velocity.

    Science.gov (United States)

    Connaboy, Chris; Naemi, Roozbeh; Brown, Susan; Psycharakis, Stelios; McCabe, Carla; Coleman, Simon; Sanders, Ross

    2016-01-01

    The optimisation of undulatory underwater swimming is highly important in competitive swimming performance. Nineteen kinematic variables were identified from previous research undertaken to assess undulatory underwater swimming performance. The purpose of the present study was to determine which kinematic variables were key to the production of maximal undulatory underwater swimming velocity. Kinematic data at maximal undulatory underwater swimming velocity were collected from 17 skilled swimmers. A series of separate backward-elimination analysis of covariance models was produced with cycle frequency and cycle length as dependent variables (DVs) and participant as a fixed factor, as including cycle frequency and cycle length would explain 100% of the maximal swimming velocity variance. The covariates identified in the cycle-frequency and cycle-length models were used to form the saturated model for maximal swimming velocity. The final parsimonious model identified three covariates (maximal knee joint angular velocity, maximal ankle angular velocity and knee range of movement) as determinants of the variance in maximal swimming velocity (adjusted-r2 = 0.929). However, when participant was removed as a fixed factor there was a large reduction in explained variance (adjusted r2 = 0.397) and only maximal knee joint angular velocity continued to contribute significantly, highlighting its importance to the production of maximal swimming velocity. The reduction in explained variance suggests an emphasis on inter-individual differences in undulatory underwater swimming technique and/or anthropometry. Future research should examine the efficacy of other anthropometric, kinematic and coordination variables to better understand the production of maximal swimming velocity and consider the importance of individual undulatory underwater swimming techniques when interpreting the data.

  8. Critique of the angular momentum sum rules and a new angular momentum sum rule

    NARCIS (Netherlands)

    Bakker, B.L.G.; Leader, E.; Trueman, T. L.

    2004-01-01

    We present a study of the tensorial structure of the hadronic matrix elements of the angular momentum operators J. Well known results in the literature are shown to be incorrect, and we have taken pains to derive the correct expressions in three different ways, two involving explicit physical wave

  9. Inefficient Angular Momentum Transport in Accretion Disk Boundary Layers: Angular Momentum Belt in the Boundary Layer

    Science.gov (United States)

    Belyaev, Mikhail A.; Quataert, Eliot

    2018-04-01

    We present unstratified 3D MHD simulations of an accretion disk with a boundary layer (BL) that have a duration ˜1000 orbital periods at the inner radius of the accretion disk. We find the surprising result that angular momentum piles up in the boundary layer, which results in a rapidly rotating belt of accreted material at the surface of the star. The angular momentum stored in this belt increases monotonically in time, which implies that angular momentum transport mechanisms in the BL are inefficient and do not couple the accretion disk to the star. This is in spite of the fact that magnetic fields are advected into the BL from the disk and supersonic shear instabilities in the BL excite acoustic waves. In our simulations, these waves only carry a small fraction (˜10%) of the angular momentum required for steady state accretion. Using analytical theory and 2D viscous simulations in the R - ϕ plane, we derive an analytical criterion for belt formation to occur in the BL in terms of the ratio of the viscosity in the accretion disk to the viscosity in the BL. Our MHD simulations have a dimensionless viscosity (α) in the BL that is at least a factor of ˜100 smaller than that in the disk. We discuss the implications of these results for BL dynamics and emission.

  10. Visual image quality assessment with sensor motion : Effect of recording and presentation velocity

    NARCIS (Netherlands)

    Bijl, P.

    2010-01-01

    To assess the effect of motion on observer performance with an undersampled uncooled thermal imager, moving imagery from a static scene was recorded at nine different angular velocities ranging from 0 (static) to 1 pixel/frame by use of a tilted rotating mirror. The scene contained a thermal acuity

  11. Theory of Rapidly Oscillating Electron Angular Distributions in Slow Ion-Atom Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Macek, J.H.; Ovchinnikov, S.Y. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1501 (United States)]|[Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)

    1998-03-01

    A general expression for the ionization amplitude in slow ion-atom collisions is derived. The expression is inverted to obtain adiabatic electronic wave functions at complex values of the internuclear distance. It is shown that beating between {sigma} and {pi} components of electronic wave functions gives rise to rapid oscillations of electron angular distributions with ion velocity v . These rapid oscillations measure the real part of that eigenvalue whose imaginary part gives the well-known Wannier exponent. {copyright} {ital 1998} {ital The American Physical Society}

  12. An EM Induction Hi-Speed Rotation Angular Rate Sensor.

    Science.gov (United States)

    Li, Kai; Li, Yuan; Han, Yan

    2017-03-17

    A hi-speed rotation angular rate sensor based on an electromagnetic induction signal is proposed to provide a possibility of wide range measurement of high angular rates. An angular rate sensor is designed that works on the principle of electromagnetism (EM) induction. In addition to a zero-phase detection technique, this sensor uses the feedback principle of magnetic induction coils in response to a rotating magnetic field. It solves the challenge of designing an angular rate sensor that is suitable for both low and high rotating rates. The sensor was examined for angular rate measurement accuracy in simulation tests using a rotary table. The results show that it is capable of measuring angular rates ranging from 1 rps to 100 rps, with an error within 1.8‰ of the full scale (FS). The proposed sensor is suitable to measurement applications where the rotation angular rate is widely varied, and it contributes to design technology advancements of real-time sensors measuring angular acceleration, angular rate, and angular displacement of hi-speed rotary objects.

  13. An EM Induction Hi-Speed Rotation Angular Rate Sensor

    Directory of Open Access Journals (Sweden)

    Kai Li

    2017-03-01

    Full Text Available A hi-speed rotation angular rate sensor based on an electromagnetic induction signal is proposed to provide a possibility of wide range measurement of high angular rates. An angular rate sensor is designed that works on the principle of electromagnetism (EM induction. In addition to a zero-phase detection technique, this sensor uses the feedback principle of magnetic induction coils in response to a rotating magnetic field. It solves the challenge of designing an angular rate sensor that is suitable for both low and high rotating rates. The sensor was examined for angular rate measurement accuracy in simulation tests using a rotary table. The results show that it is capable of measuring angular rates ranging from 1 rps to 100 rps, with an error within 1.8‰ of the full scale (FS. The proposed sensor is suitable to measurement applications where the rotation angular rate is widely varied, and it contributes to design technology advancements of real-time sensors measuring angular acceleration, angular rate, and angular displacement of hi-speed rotary objects.

  14. Angular correlation of the N+ ions produced in the dissociative double ionization of nitrogen

    International Nuclear Information System (INIS)

    Ezell, R.L.; Edwards, A.K.; Wood, R.M.

    1984-01-01

    The double ionization of N 2 by He + projectiles was studied by measuring the angular correlation between the two N + ions emitted in the dissociation of N 2+ 2 molecular ions. If there were no recoil velocity imposed on the N 2+ 2 ion in the initial ionizing collision, and thermal effects were neglected, the pair of N + ions would have equal and opposite velocity vectors in the laboratory frame of reference. Measuring the coincidence yield of pairs of N + ions as a function of the angle between their velocity vectors permits an estimate to be made of the component of momentum transferred to the N 2+ 2 parent ions in the beam direction. The results presented in this report show the recoil velocity to be considerably less than the mean thermal velocity of N 2 molecules at room temperature. We also report mesurements of the relative cross section for N + production from N 2+ 2 as a function of the orientation of the N 2 target molecules relative to the projectile beam axis

  15. Contributions of upper limb rotations to racket velocity in table tennis backhands against topspin and backspin.

    Science.gov (United States)

    Iino, Yoichi; Mori, Teruaki; Kojima, Takeji

    2008-02-01

    The purpose of this study was to assess the contributions of racket arm joint rotations to the racket tip velocity at ball impact in table tennis topspin backhands against topspin and backspin using the method of Sprigings et al. (1994). Two cine cameras were used to determine three-dimensional motions of the racket arm and racket, and the contributions of the rotations for 11 male advanced table tennis players. The racket upward velocity at impact was significantly higher in the backhand against backspin than against topspin, while the forward velocity was not significantly different between the two types of backhands. The negative contribution of elbow extension to the upward velocity was significantly less against backspin than against topspin. The contribution of wrist dorsiflexion to the upward velocity was significantly greater against backspin than against topspin. The magnitudes of the angular velocities of elbow extension and wrist dorsiflexion at impact were both similar between the two types of backhands. Our results suggest that the differences in contributions of elbow extension and wrist dorsiflexion to the upward velocity were associated with the difference in upper limb configuration rather than in magnitudes of their angular velocities.

  16. Inhomogeneous Broadening in Perturbed Angular Correlation Spectroscopy

    Science.gov (United States)

    Bunker, Austin; Adams, Mike; Hodges, Jeffery; Park, Tyler; Stufflebeam, Michael; Evenson, William; Matheson, Phil; Zacate, Matthew

    2009-10-01

    Our research concerns the effect of a static distribution of defects on the net electric field gradient (EFG) within crystal structures. Defects and vacancies perturb the distribution of gamma rays emitted from radioactive probe nuclei within the crystal. These defects and vacancies produce a net EFG at the site of the probe which causes the magnetic quadrupole moment of the nucleus of the probe to precess about the EFG. The net EFG, which is strongly dependent upon the defect concentration, perturbs the angular correlation (PAC) of the gamma rays, and is seen in the damping of the perturbation function, G2(t), in time and broadening of the spectral peaks in the Fourier transform. We have used computer simulations to study the probability distribution of EFG tensor components in order to uncover the concentration dependence of G2(t). This in turn can be used to analyze experimental PAC data and quantitatively describe properties of the crystal.

  17. Topological photonic orbital-angular-momentum switch

    Science.gov (United States)

    Luo, Xi-Wang; Zhang, Chuanwei; Guo, Guang-Can; Zhou, Zheng-Wei

    2018-04-01

    The large number of available orbital-angular-momentum (OAM) states of photons provides a unique resource for many important applications in quantum information and optical communications. However, conventional OAM switching devices usually rely on precise parameter control and are limited by slow switching rate and low efficiency. Here we propose a robust, fast, and efficient photonic OAM switch device based on a topological process, where photons are adiabatically pumped to a target OAM state on demand. Such topological OAM pumping can be realized through manipulating photons in a few degenerate main cavities and involves only a limited number of optical elements. A large change of OAM at ˜10q can be realized with only q degenerate main cavities and at most 5 q pumping cycles. The topological photonic OAM switch may become a powerful device for broad applications in many different fields and motivate a topological design of conventional optical devices.

  18. Coherent control of photoelectron wavepacket angular interferograms

    International Nuclear Information System (INIS)

    Hockett, P; Wollenhaupt, M; Baumert, T

    2015-01-01

    Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light–matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable. (paper)

  19. Coherent control of photoelectron wavepacket angular interferograms

    Science.gov (United States)

    Hockett, P.; Wollenhaupt, M.; Baumert, T.

    2015-11-01

    Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light-matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable.

  20. Angular filter refractometry analysis using simulated annealing.

    Science.gov (United States)

    Angland, P; Haberberger, D; Ivancic, S T; Froula, D H

    2017-10-01

    Angular filter refractometry (AFR) is a novel technique used to characterize the density profiles of laser-produced, long-scale-length plasmas [Haberberger et al., Phys. Plasmas 21, 056304 (2014)]. A new method of analysis for AFR images was developed using an annealing algorithm to iteratively converge upon a solution. A synthetic AFR image is constructed by a user-defined density profile described by eight parameters, and the algorithm systematically alters the parameters until the comparison is optimized. The optimization and statistical uncertainty calculation is based on the minimization of the χ 2 test statistic. The algorithm was successfully applied to experimental data of plasma expanding from a flat, laser-irradiated target, resulting in an average uncertainty in the density profile of 5%-20% in the region of interest.

  1. Nuclear scissors modes and hidden angular momenta

    Energy Technology Data Exchange (ETDEWEB)

    Balbutsev, E. B., E-mail: balbuts@theor.jinr.ru; Molodtsova, I. V. [Joint Institute for Nuclear Research (Russian Federation); Schuck, P. [Université Paris-Sud, Institut de Physique Nucléaire, IN2P3–CNRS (France)

    2017-01-15

    The coupled dynamics of low-lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time-Dependent Hartree–Fock–Bogoliubov equations. The model of the harmonic oscillator including spin–orbit potential plus quadrupole–quadrupole and spin–spin interactions is considered. New low-lying spin-dependent modes are analyzed. Special attention is paid to the scissors modes. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes.

  2. Angular reduction in multiparticle matrix elements

    International Nuclear Information System (INIS)

    Lehman, D.R.; Parke, W.C.

    1989-01-01

    A general method for reduction of coupled spherical harmonic products is presented. When the total angular coupling is zero, the reduction leads to an explicitly real expression in the scalar products of the unit vector arguments of the spherical harmonics. For nonscalar couplings, the reduction gives Cartesian tensor forms for the spherical harmonic products; tensors built from the physical vectors in the original expression. The reduction for arbitrary couplings is given in closed form, making it amenable to symbolic manipulation on a computer. The final expressions do not depend on a special choice of coordinate axes, nor do they contain azimuthal quantum number summations, or do they have complex tensor terms for couplings to a scalar; consequently, they are easily interpretable from the properties of the physical vectors they contain

  3. Chiral symmetries associated with angular momentum

    International Nuclear Information System (INIS)

    Bhattacharya, M; Kleinert, M

    2014-01-01

    In quantum mechanics courses, symmetries of a physical system are usually introduced as operators which commute with the Hamiltonian. In this paper we will consider chiral symmetries which anticommute with the Hamiltonian. Typically, introductory courses at the (under)graduate level do not discuss these simple, useful and beautiful symmetries at all. The first time a student encounters them is when the Dirac equation is discussed in a course on relativistic quantum mechanics, or when particle–hole symmetry is studied in the context of superconductivity. In this paper, we will show how chiral symmetries can be simply elucidated using the theory of angular momentum, which is taught in virtually all introductory quantum mechanics courses. (paper)

  4. Cierre angular primario: opciones quirúrgicas

    Directory of Open Access Journals (Sweden)

    Henry Pérez-González

    2014-10-01

    Full Text Available Se realizó una revisión bibliográfica con el objetivo de exponer las principales opciones quirúrgicas en el tratamiento del cierre angular primario efectuando una búsqueda de los principales artículos científicos de los últimos años, así como de la literatura impresa que incluye el tema, siendo seleccionados los contenidos más relevantes para la confección del informe final. Las opciones de tratamiento incluyen la cirugía láser (iridotomía, iridoplastia y la cirugía incisional (filtrante, extracción del cristalino, dependiendo de los factores fisiopatológicos involucrados y la forma clínica en el momento del diagnóstico.

  5. Untangling Galaxy Components - The Angular Momentum Parameter

    Science.gov (United States)

    Tabor, Martha; Merrifield, Michael; Aragon-Salamanca, Alfonso

    2017-06-01

    We have developed a new technique to decompose Integral Field spectral data cubes into separate bulge and disk components, allowing us to study the kinematic and stellar population properties of the individual components and how they vary with position. We present here the application of this method to a sample of fast rotator early type galaxies from the MaNGA integral field survey, and demonstrate how it can be used to explore key properties of the individual components. By extracting ages, metallicities and the angular momentum parameter lambda of the bulges and disks, we show how this method can give us new insights into the underlying structure of the galaxies and discuss what this can tell us about their evolution history.

  6. Angular biasing in implicit Monte-Carlo

    International Nuclear Information System (INIS)

    Zimmerman, G.B.

    1994-01-01

    Calculations of indirect drive Inertial Confinement Fusion target experiments require an integrated approach in which laser irradiation and radiation transport in the hohlraum are solved simultaneously with the symmetry, implosion and burn of the fuel capsule. The Implicit Monte Carlo method has proved to be a valuable tool for the two dimensional radiation transport within the hohlraum, but the impact of statistical noise on the symmetric implosion of the small fuel capsule is difficult to overcome. We present an angular biasing technique in which an increased number of low weight photons are directed at the imploding capsule. For typical parameters this reduces the required computer time for an integrated calculation by a factor of 10. An additional factor of 5 can also be achieved by directing even smaller weight photons at the polar regions of the capsule where small mass zones are most sensitive to statistical noise

  7. Angular Position Tracking Control of a Quadcopter

    Directory of Open Access Journals (Sweden)

    T. V. Glazkov

    2017-01-01

    Full Text Available The paper dwells on tracking the quad-copter angular position with desired quality parameters of transient processes. The aerial vehicle is considered as a rigid body with six degrees of freedom.  A full rigid body quad-copter mathematical model is considered without the assumption of smallness of the Euler angles.Among the most well known methods of non-linear stabilization are feedback linearization and backstepping. The backstepping approach allows us to have an effective solution of the stabilization problems with uncertainties available in the system. However, in synthesis of the feedback through backstepping, there is still an urgent issue: how to ensure desirable quality of transients in the closed-loop system. The paper presents a solution of this problem using as an example the tracking a given (programmed change of the angular position of a quad-copter.The control algorithms obtained in this paper are implemented using the Rolling Spider MATLAB Toolbox (ROSMAT tool package on the Parrot Rolling Spider quad-copter. A numerical simulation and experiments have shown the efficiency of obtained control laws, with the transient processes taking into account the desired quality indicators. However, the experiments showed that lack of terms in the mathematical model to describe the aerodynamic effects, resulted in the instability of the quad-copter flight near the obstacle (the effect of the reflected airflow.Further research can be aimed at solving the control problem in question using a mathematical model of the quad-copter motion that takes into account various aerodynamic effects.One of the potential application areas for the theoretical results, obtained in the paper, is to solve the problems of automatic control of unmanned aerial vehicles.

  8. Introduction to vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Udesen, Jesper; Hansen, Kristoffer Lindskov

    it virtually impossible to compensate for the factor and obtain correct velocity estimates for either CFM or spectral velocity estimation. This talk will describe methods for finding the correct velocity by estimating both the axial and lateral component of the velocity vector. The transverse oscillation...... method introduces an ultrasound field that oscillation not only along the ultrasound beam both also transverse to it to estimate both the lateral and axial velocity for the full velocity vector. The correct velocity magnitude can be found from this as well as the instantaneous angle. This can be obtained...... over the full region of interest and a real time image at a frame rate of 20 Hz can be displayed. Real time videos have been obtained from both our research systems and from commercial BK Medical scanners. The vector velocity images reveal the full complexity of the human blood flow. It is easy to see...

  9. SELF-GRAVITY AND ANGULAR MOMENTUM TRANSPORT IN EXTENDED GALACTIC DISKS

    International Nuclear Information System (INIS)

    McNally, C. P.; Wadsley, J.; Couchman, H. M. P.

    2009-01-01

    We demonstrate a significant difference in the angular momentum transport properties of galactic disks between regions in which the interstellar medium is single phase or two phase. Our study is motivated by observations of H I in extended galactic disks which indicate velocity dispersions of nonthermal origin, suggesting that turbulence in the gas may be contributing significantly to the observed dispersion. To address this, we have implemented a shearing-box framework within the FLASH code. The new code was used to perform local simulations of galactic disks that incorporate differential rotation, self-gravity, vertical stratification, hydrodynamics, and cooling. These simulations explore plausible mechanisms for driving turbulent motions via the thermal and self-gravitational instabilities coupling to differential rotation. Where a two-phase medium develops, gravitational angular momentum transporting stresses are much greater, creating a possible mechanism for transferring energy from galactic rotation to turbulence. In simulations where the disk conditions do not trigger the formation of a two-phase medium, it is found that perturbations to the flow damp without leading to a sustained mechanism for driving turbulence. The differing angular momentum transport properties of the single- and two-phase regimes of the disk suggest that a significant, dynamically motivated division can be drawn between the two, even when this division occurs far outside the star formation cutoff in a galactic disk.

  10. Examples of Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Hansen, Peter M.; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    To measure blood flow velocity in vessels with conventional ultrasound, the velocity is estimated along the direction of the emitted ultrasound wave. It is therefore impossible to obtain accurate information on blood flow velocity and direction, when the angle between blood flow and ultrasound wa...

  11. Angularly resolved electron wave packet interferences

    International Nuclear Information System (INIS)

    Varju, K; Johnsson, P; Mauritsson, J; Remetter, T; Ruchon, T; Ni, Y; Lepine, F; Kling, M; Khan, J; Schafer, K J; Vrakking, M J J; L'Huillier, A

    2006-01-01

    We study experimentally the ionization of argon atoms by a train of attosecond pulses in the presence of a strong infrared laser field, using a velocity map imaging technique. The recorded momentum distribution strongly depends on the delay between the attosecond pulses and the laser field. We interpret the interference patterns observed for different delays using numerical and analytical calculations within the strong field approximation

  12. Angularly resolved electron wave packet interferences

    Energy Technology Data Exchange (ETDEWEB)

    Varju, K [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden); Johnsson, P [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden); Mauritsson, J [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden); Remetter, T [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden); Ruchon, T [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden); Ni, Y [FOM-Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); Lepine, F [FOM-Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); Kling, M [FOM-Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); Khan, J [FOM-Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); Schafer, K J [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Vrakking, M J J [FOM-Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); L' Huillier, A [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden)

    2006-09-28

    We study experimentally the ionization of argon atoms by a train of attosecond pulses in the presence of a strong infrared laser field, using a velocity map imaging technique. The recorded momentum distribution strongly depends on the delay between the attosecond pulses and the laser field. We interpret the interference patterns observed for different delays using numerical and analytical calculations within the strong field approximation.

  13. Velocity dependence of eccentric strength in young and old men: the need for speed!

    Science.gov (United States)

    Power, Geoffrey A; Makrakos, Demetri P; Stevens, Daniel E; Rice, Charles L; Vandervoort, Anthony A

    2015-07-01

    Older adults better maintain eccentric strength relative to isometric strength, as indicated by a higher ratio of eccentric:isometric torque as compared with younger adults. The effect of increasing angular velocities (>200°/s) on the age-related maintenance of eccentric strength has not been tested and thus it is unknown whether the eccentric:isometric ratio is velocity dependent in old age. The purpose of this study was to investigate eccentric strength of the ankle dorsiflexors over a large range of lengthening angular velocities in young and older men. Isometric neuromuscular properties were assessed on a HUMAC NORM dynamometer. Nine young (∼24 years) and 9 older (∼76 years) healthy men performed maximal voluntary eccentric contractions at angular velocities of 15-360°/s. Despite near full voluntary activation (>95%), the older men were ∼30% weaker than the young men for isometric strength (P eccentric:isometric ratio than young men (P eccentric strength increased as velocity increased up to 120°/s (P eccentric strength at 15°/s was ∼20% and ∼40% greater than isometric strength (P eccentric strength was ∼50% and ∼90% greater, respectively (P eccentric:isometric ratio of torque production.

  14. Acoustic beam control in biomimetic projector via velocity gradient

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiaowei; Dong, Erqian; Song, Zhongchang [Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, Xiamen University, Xiamen 361005 (China); Zhang, Yu, E-mail: yuzhang@xmu.edu.cn, E-mail: dzk@psu.edu; Tang, Liguo [Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, Xiamen University, Xiamen 361005 (China); State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005 (China); Cao, Wenwu, E-mail: yuzhang@xmu.edu.cn, E-mail: dzk@psu.edu [Department of Mathematics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Li, Songhai [Sanya Key Laboratory of Marin Mammal and Marine Bioacoustics, Sanya Institute of Deep-Sea Science and Engineering, Chinese Academy of Science, Sanya 57200 (China); Zhang, Sai [Faculty of Science, Jiangsu University, Zhenjiang 212013 (China)

    2016-07-04

    A biomimetic projector (BioP) based on computerized tomography of pygmy sperm whale's biosonar system has been designed using gradient-index (GRIN) material. The directivity of this BioP device was investigated as function of frequency and the velocity gradient of the GRIN material. A strong beam control over a broad bandwidth at the subwavelength scale has been achieved. Compared with a bare subwavelength source, the main lobe pressure of the BioP is about five times as high and the angular resolution is one order of magnitude better. Our results indicate that this BioP has excellent application potential in miniaturized underwater sonars.

  15. Measurement of torsional vibration to detect angular misalignment through the modulated square wave of an encoder

    Science.gov (United States)

    Meroño, P. A.; Gómez, F. C.; Marín, F.; Zaghar, L.

    2017-02-01

    One of the widely used processes to measure torsional vibration focuses on the analysis of a square signal from a device set in the machine shaft. The tools used for this purpose usually consist of a toothed wheel connected to an appropriate transducer, of an electromagnetic or optic type, which provides a square wave signal. If the rotation velocity is constant, the signal pulses are the same width, but when the velocity changes, the width of the pulses changes too, lengthening or shortening its width, resulting in a frequency modulated signal. When the shafts of the machines are misaligned angularly, the average speed changes due to variable torque action, so that spectral features of modulated signal show frequency components that are explained by the Bessel Functions. This work shows that these components are caused by a carrying (constant average speed) and a modulator signal (variable turning speed) between the harmonics surrounding the central frequency. Besides, it may also test their relationship with the presence of angular misalignment in the coupled-machine shafts. In addition, an iterative method is applied to construct the frequency spectral diagram of the induced square signal, once the appropriate modulation indices of the Bessel functions have been calculated. To compare and validate the method, different bench tests have been performed using pulse signal and laser interferometry.

  16. Discrete time interval measurement system: fundamentals, resolution and errors in the measurement of angular vibrations

    International Nuclear Information System (INIS)

    Gómez de León, F C; Meroño Pérez, P A

    2010-01-01

    The traditional method for measuring the velocity and the angular vibration in the shaft of rotating machines using incremental encoders is based on counting the pulses at given time intervals. This method is generically called the time interval measurement system (TIMS). A variant of this method that we have developed in this work consists of measuring the corresponding time of each pulse from the encoder and sampling the signal by means of an A/D converter as if it were an analog signal, that is to say, in discrete time. For this reason, we have denominated this method as the discrete time interval measurement system (DTIMS). This measurement system provides a substantial improvement in the precision and frequency resolution compared with the traditional method of counting pulses. In addition, this method permits modification of the width of some pulses in order to obtain a mark-phase on every lap. This paper explains the theoretical fundamentals of the DTIMS and its application for measuring the angular vibrations of rotating machines. It also displays the required relationship between the sampling rate of the signal, the number of pulses of the encoder and the rotating velocity in order to obtain the required resolution and to delimit the methodological errors in the measurement

  17. A Novel Two-Velocity Method for Elaborate Isokinetic Testing of Knee Extensors.

    Science.gov (United States)

    Grbic, Vladimir; Djuric, Sasa; Knezevic, Olivera M; Mirkov, Dragan M; Nedeljkovic, Aleksandar; Jaric, Slobodan

    2017-09-01

    Single outcomes of standard isokinetic dynamometry tests do not discern between various muscle mechanical capacities. In this study, we aimed to (1) evaluate the shape and strength of the force-velocity relationship of knee extensors, as observed in isokinetic tests conducted at a wide range of angular velocities, and (2) explore the concurrent validity of a simple 2-velocity method. Thirteen physically active females were tested for both the peak and averaged knee extensor concentric force exerted at the angular velocities of 30°-240°/s recorded in the 90°-170° range of knee extension. The results revealed strong (0.960velocity relationships that depict the maximum muscle force (i.e. the force-intercept), velocity (velocity-intercept), and power (their product). Moreover, the line drawn through only the 60° and 180°/s data (the '2-velocity method') revealed a high level of agreement with the force-velocity relationship obtained (0.76velocity method could therefore be developed into a standard method for isokinetic testing of mechanical capacities of knee extensors and, if supported by further research, other muscles. This brief and fatigue-free testing procedure could discern between muscle force, velocity, and power-producing capacities. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Inheritance of resistance to angular leaf spot in yellow beans ...

    African Journals Online (AJOL)

    Angular leaf spot (Phaeoisariopsis griseola (Sacc) is an important disease of common bean (Phaseolus vulgaris L.) in most parts of Africa, causing yield losses of 40-80%. This study was carried out to determine the inheritance of resistance to angular leaf spot in yellow beans. Biparental crosses were done between ...

  19. Prospects of Measuring the Angular Power Spectrum of the Diffuse ...

    Indian Academy of Sciences (India)

    Review. J. Astrophys. Astr. (2016) 37: 35. DOI: 10.1007/s12036-016-9413-x. Prospects of Measuring the Angular Power Spectrum of the Diffuse. Galactic .... In this section we briefly review the Tapered Gridded Estimator (TGE), the details ... of the product of the primary beam pattern A(θ) and δI(θ) the angular fluctuation.

  20. Learning web development with Bootstrap and AngularJS

    CERN Document Server

    Radford, Stephen

    2015-01-01

    Whether you know a little about Bootstrap or AngularJS, or you're a complete beginner, this book will enhance your capabilities in both frameworks and you'll build a fully functional web app. A working knowledge of HTML, CSS, and JavaScript is required to fully get to grips with Bootstrap and AngularJS.

  1. 3D printed bio-inspired angular acceleration sensor

    NARCIS (Netherlands)

    van Tiem, Joël; Groenesteijn, Jarno; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.

    2015-01-01

    Abstract—We present a biomimetic angular acceleration sensor inspired by the vestibular system, as found e.g. in mammals and fish. The sensor consist of a fluid filled circular channel. When exposed to angular accelerations the fluid flows relative to the channel. Read-out is based on

  2. inheritance of resistance to angular leaf spot in yellow beans ...

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    Susceptible. II -indeterminate erect; III -indeterminate semi-prostate; ALS = Angular leaf spot. Isolation of Phaeoisariopsis griseola and plant inoculation. Isolation of angular leaf spot was made from lesions of naturally infected bean leaves showing fungal sporulation. In the case of non-sporulating lesions, the fungus was.

  3. Angular sensitivity of blowfly photoreceptors : broadening by artificial electrical coupling

    NARCIS (Netherlands)

    Smakman, J.G.J.; Stavenga, D.G.

    1987-01-01

    1. Electrical coupling between R1-6 photoreceptors was investigated by measuring angular sensitivities and quantum bumps. 2. Recordings were made from two extreme types of cells: Type a: cells with a diffraction-like angular sensitivity profile. Only large bumps could be obtained from these cells.

  4. Epidemiology Of Angular Deformities Of The Knee In Children In ...

    African Journals Online (AJOL)

    Background: Bony problems such as angular deformities and metabolic bone disease are of high frequency in Nigeria. Objective: The aim of this study was to define the pattern of presentation in children with angular deformities of the knee. Methodology: It was an 18-month prospective study involving children aged ...

  5. Fundamental methods to measure the orbital angular momentum of light

    NARCIS (Netherlands)

    Berkhout, Gregorius Cornelis Gerardus (Joris)

    2011-01-01

    Light is a ubiquitous carrier of information. This information can be encoded in the intensity, direction, frequency and polarisation of the light and, which was described more recently, in its orbital angular momentum. Although creating light beams with orbital angular momentum is relatively easy,

  6. Considerations on the determining factors of the angular distribution of emitted particles in laser ablation

    International Nuclear Information System (INIS)

    Konomi, I.; Motohiro, T.; Kobayashi, T.; Asaoka, T.

    2010-01-01

    Simulations of particles which are emitted in laser ablation have been performed by the method of Direct Simulation Monte Carlo to investigate the deposition profiles of the emitted particles. The influences of the temperature, pressure and stream velocity of the initial evaporated layer formed during laser ablation process on the profile of the deposited film have been examined. It is found that the temperature gives a minor influence on the deposition profile, whereas the stream velocity and the pressure of the initial evaporated layer have a greater impact on the deposition profile. The energy in the direction of surface normal (E perpendicular ) and that in the parallel direction of the surface (E || ) are shown to increase and decrease, respectively after the laser irradiation due to collisions between the emitted particles, and this trend is magnified as the pressure increases. As a consequence, the stream velocity in the direction of surface normal increases with the increase in the pressure. A mechanism of the phenomenon that a metal with a lower sublimation energy shows a broader angular distribution of emitted particles is presented. It is suggested that low density of evaporated layer of a metal with a low sublimation energy at its melting point decreases the number of collisions in the layer, leading to the low stream velocity in the direction of surface normal, which results in the broader deposition profile of the emitted particles.

  7. Optical communications beyond orbital angular momentum

    Science.gov (United States)

    Rosales-Guzmán, Carmelo; Trichili, Abderrahmen; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-09-01

    Current optical communication technologies are predicted to face a bandwidth capacity limit in the near future. The nature of the limitation is fundamental rather than technological and is set by nonlinearities in optical fibers. One solution, suggested over 30 years ago, comprises the use of spatial modes of light as information carriers. Along this direction, light beams endowed with orbital angular momentum (OAM) have been demonstrated as potential information carriers in both, free space and fibres. However, recent studies suggest that purely OAM modes does not increase the bandwidth of optical communication systems. In fact, in all work to date, only the azimuthal component of transverse spatial modes has been used. Crucially, all transverse spatial modes require two degrees of freedom to be described; in the context of Laguerre-Gaussian (LGp`) beams these are azimuthal (l) and radial (p), the former responsible for OAM. Here, we demonstrate a technique where both degrees of freedom of LG modes are used as information carrier over free space. We transfer images encoded using 100 spatial modes in three wavelengths as our basis, and employ a spatial demultiplexing scheme that detects all 100 modes simultaneously. Our scheme is a hybrid of MIMO and SMM, and serves as a proof-of-principle demonstration. The cross-talk between the modes is small and independent of whether OAM modes are used or not.

  8. CLASS: The Cosmology Large Angular Scale Surveyor

    Science.gov (United States)

    Essinger-Hileman, Thomas; Ali, Aamir; Amiri, Mandana; Appel, John W.; Araujo, Derek; Bennett, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.; hide

    2014-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravitational wave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array of four telescopes operating from a high-altitude site in the Atacama Desert in Chile. CLASS will survey 70% of the sky in four frequency bands centered at 38, 93, 148, and 217 GHz, which are chosen to straddle the Galactic-foreground minimum while avoiding strong atmospheric emission lines. This broad frequency coverage ensures that CLASS can distinguish Galactic emission from the CMB. The sky fraction of the CLASS survey will allow the full shape of the primordial B-mode power spectrum to be characterized, including the signal from reionization at low-length. Its unique combination of large sky coverage, control of systematic errors, and high sensitivity will allow CLASS to measure or place upper limits on the tensor-to-scalar ratio at a level of r = 0:01 and make a cosmic-variance-limited measurement of the optical depth to the surface of last scattering, tau. (c) (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  9. Angular distributions of sputtered particles from NiTi alloy

    International Nuclear Information System (INIS)

    Neshev, I.; Hamishkeev, V.; Chernysh, V.S.; Postnikov, S.; Mamaev, B.

    1993-01-01

    The angular distributions of sputtered Ni and Ti from a polycrystalline NiTi (50-50%) alloy are investigated by Auger electron spectroscopy and Rutherford backscattering spectroscopy. A difference in the angular distributions is observed with Ni being sputtered preferentially near the surface normal. A computer program for the calculation of the angular distributions of constituents sputtered from binary targets is created and used. The mechanisms responsible for the observed differences in the angular distributions are discussed. It is found that the collisional cascade theory is not directly applicable to the results of the constituents' angular distributions obtained in the presence of oxygen. The fitted coefficients of bombardment-induced segregation are found to be greater than the experimentally obtained ones. (author)

  10. Hot nuclei: high temperatures, high angular momenta

    International Nuclear Information System (INIS)

    Guerreau, D.

    1991-01-01

    A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs

  11. Control rod velocity limiter

    International Nuclear Information System (INIS)

    Cearley, J.E.; Carruth, J.C.; Dixon, R.C.; Spencer, S.S.; Zuloaga, J.A. Jr.

    1986-01-01

    This patent describes a velocity control arrangement for a reciprocable, vertically oriented control rod for use in a nuclear reactor in a fluid medium, the control rod including a drive hub secured to and extending from one end therefrom. The control device comprises: a toroidally shaped control member spaced from and coaxially positioned around the hub and secured thereto by a plurality of spaced radial webs thereby providing an annular passage for fluid intermediate the hub and the toroidal member spaced therefrom in coaxial position. The side of the control member toward the control rod has a smooth generally conical surface. The side of the control member away from the control rod is formed with a concave surface constituting a single annular groove. The device also comprises inner and outer annular vanes radially spaced from one another and spaced from the side of the control member away from the control rod and positioned coaxially around and spaced from the hub and secured thereto by spaced radial webs thereby providing an annular passage for fluid intermediate the hub and the vanes. The vanes are angled toward the control member, the outer edge of the inner vane being closer to the control member and the inner edge of the outer vane being closer to the control member. When the control rod moves in the fluid in the direction toward the drive hub the vanes direct a flow of fluid turbulence which provides greater resistance to movement of the control rod in the direction toward the drive hub than in the other direction

  12. Velocity storage mechanism in zebrafish larvae

    Science.gov (United States)

    Chen, Chien-Cheng; Bockisch, Christopher J; Bertolini, Giovanni; Olasagasti, Itsaso; Neuhauss, Stephan C F; Weber, Konrad P; Straumann, Dominik; Ying-Yu Huang, Melody

    2014-01-01

    Abstract The optokinetic reflex (OKR) and the angular vestibulo-ocular reflex (aVOR) complement each other to stabilize images on the retina despite self- or world motion, a joint mechanism that is critical for effective vision. It is currently hypothesized that signals from both systems integrate, in a mathematical sense, in a network of neurons operating as a velocity storage mechanism (VSM). When exposed to a rotating visual surround, subjects display the OKR, slow following eye movements frequently interrupted by fast resetting eye movements. Subsequent to light-off during optokinetic stimulation, eye movements do not stop abruptly, but decay slowly, a phenomenon referred to as the optokinetic after-response (OKAR). The OKAR is most likely generated by the VSM. In this study, we observed the OKAR in developing larval zebrafish before the horizontal aVOR emerged. Our results suggest that the VSM develops prior to and without the need for a functional aVOR. It may be critical to ocular motor control in early development as it increases the efficiency of the OKR. PMID:24218543

  13. Sodium Velocity Maps on Mercury

    Science.gov (United States)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  14. Control of Angular Intervals for Angle-Multiplexed Holographic Memory

    Science.gov (United States)

    Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Shimidzu, Naoki

    2009-03-01

    In angle-multiplexed holographic memory, the full width at half maximum of the Bragg selectivity curves is dependent on the angle formed between the medium and incident laser beams. This indicates the possibility of high density and high multiplexing number by varying the angular intervals between adjacent holograms. We propose an angular interval scheduling for closely stacking holograms into medium even when the angle range is limited. We obtained bit error rates of the order of 10-4 under the following conditions: medium thickness of 1 mm, laser beam wavelength of 532 nm, and angular multiplexing number of 300.

  15. Fission fragment angular distribution in heavy ion induced fission

    Directory of Open Access Journals (Sweden)

    S. Soheyli

    2006-06-01

    Full Text Available   We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a without neutron correction and b with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the average emitted neutron from compound nuclei considering the best fit for each system.

  16. Fission fragment angular distribution in heavy ion induced fission

    OpenAIRE

    S. Soheyli; I. Ziaeian

    2006-01-01

      We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a) without neutron correction and b) with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the averag...

  17. Angular absorption of iridium - ICW12 needles: practical considerations

    International Nuclear Information System (INIS)

    Szymczyk, W.; Lesiak, J.

    1984-01-01

    An analysis was made of two potential sources of error in Ir 192 dosimetry: the effect of angular absorption and the differences in the ionization constants found in literature. Corrections for selfabsorption in the ICW12 iridium source were determined from measurements and calculations. It was found that the decrease in the dose caused by the angular absorption in the central therapeutic area of a typical implantation can exceed 5 percent. The need for employing the concept of ''constant exposure rate'' is stressed as well as that for using angular absorption in the form of absorption. 13 refs., 6 figs., 1 tab. (author)

  18. Maximum Velocities in Flexion and Extension Actions for Sport

    Directory of Open Access Journals (Sweden)

    Jessop David M.

    2016-04-01

    Full Text Available Speed of movement is fundamental to the outcome of many human actions. A variety of techniques can be implemented in order to maximise movement speed depending on the goal of the movement, constraints, and the time available. Knowing maximum movement velocities is therefore useful for developing movement strategies but also as input into muscle models. The aim of this study was to determine maximum flexion and extension velocities about the major joints in upper and lower limbs. Seven university to international level male competitors performed flexion/extension at each of the major joints in the upper and lower limbs under three conditions: isolated; isolated with a countermovement; involvement of proximal segments. 500 Hz planar high speed video was used to calculate velocities. The highest angular velocities in the upper and lower limb were 50.0 rad·s-1 and 28.4 rad·s-1, at the wrist and knee, respectively. As was true for most joints, these were achieved with the involvement of proximal segments, however, ANOVA analysis showed few significant differences (p<0.05 between conditions. Different segment masses, structures and locations produced differing results, in the upper and lower limbs, highlighting the requirement of segment specific strategies for maximal movements.

  19. Diffraction imaging and velocity analysis using oriented velocity continuation

    KAUST Repository

    Decker, Luke

    2014-08-05

    We perform seismic diffraction imaging and velocity analysis by separating diffractions from specular reflections and decomposing them into slope components. We image slope components using extrapolation in migration velocity in time-space-slope coordinates. The extrapolation is described by a convection-type partial differential equation and implemented efficiently in the Fourier domain. Synthetic and field data experiments show that the proposed algorithm is able to detect accurate time-migration velocities by automatically measuring the flatness of events in dip-angle gathers.

  20. Helicons in uniform fields. II. Poynting vector and angular momenta

    Science.gov (United States)

    Stenzel, R. L.; Urrutia, J. M.

    2018-03-01

    The orbital and spin angular momenta of helicon modes have been determined quantitatively from laboratory experiments. The current density is obtained unambiguously from three dimensional magnetic field measurements. The only approximation made is to obtain the electric field from Hall Ohm's law which is usually the case for low frequency whistler modes. This allows the evaluation of the Poynting vector from which the angular momentum is obtained. Comparing two helicon modes (m = 0 and m = 1), one can separate the contribution of angular momentum of a rotating and non-rotating wave field. The orbital angular momentum is important to assess the wave-particle interaction by the transverse Doppler shift of rotating waves which has not been considered so far.

  1. Angular Momentum Transport in Quasi-Keplerian Accretion Disks ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Keplerian accretion disk yield results that are inconsistent with the generally accepted model. If correct, the ideas proposed by Hayashi &. Matsuda would radically alter our understanding of the nature of the angular momentum transport in the disk, ...

  2. Application of instantaneous angular acceleration to diesel engine fault diagnosis

    Science.gov (United States)

    Ren, Yunpeng; Hu, Tianyou; Liu, Xin

    2005-12-01

    Diesel engine is a kind of important power generating machine, of which the running state monitoring and fault diagnosis attracts increasing attention. The theory and the method of diesel engine fault diagnosis based on angular acceleration measurement were studied, since angular acceleration contains a lot of information for diesel engine fault diagnosing and its power balance evaluating. USB data acquisition system was designed for the angular acceleration measurement, and it was composed with AVRAT09S8515 micro-processor and PDIUSBD12 USB interface IC. At the same time, the high speed micro-processor AVRAT09S8515 with unique function of automatically capturing the rising or falling edge of square wave was studied, and it was utilized in the diesel engine's crankshaft angular acceleration measuring system. The software and hardware of the whole system was designed, which supplied a whole solution to diesel engine fault diagnosis and power balance evaluation between each cylinder.

  3. Dissipation of angular momentum in light heavy ion collision

    International Nuclear Information System (INIS)

    Bhattacharya, C.; Bhattacharya, S.; Bhattacharjee, T.; Dey, A.; Kundu, S.; Krishan, K.; Banerjee, S.R.; Das, P.; Basu, S.K.

    2003-01-01

    The fragment emission has been studied and is reported how angular momentum dissipation can be estimated in a model independent manner using additional information from the fusion-fission component of the fragment emission data

  4. The search for and registration of superweak angular ground motions

    International Nuclear Information System (INIS)

    Budagov, J.; Lyablin, M.; Shirkov, G.

    2013-01-01

    The Earth's surface angular oscillations of the seismic, industrial and terrestrial origins have been registered with the high-resolution inclinometer of a new design concept. The microseismic peak was first recognized in the ground microradian motion

  5. Large-uncertainty intelligent states for angular momentum and angle

    International Nuclear Information System (INIS)

    Goette, Joerg B; Zambrini, Roberta; Franke-Arnold, Sonja; Barnett, Stephen M

    2005-01-01

    The equality in the uncertainty principle for linear momentum and position is obtained for states which also minimize the uncertainty product. However, in the uncertainty relation for angular momentum and angular position both sides of the inequality are state dependent and therefore the intelligent states, which satisfy the equality, do not necessarily give a minimum for the uncertainty product. In this paper, we highlight the difference between intelligent states and minimum uncertainty states by investigating a class of intelligent states which obey the equality in the angular uncertainty relation while having an arbitrarily large uncertainty product. To develop an understanding for the uncertainties of angle and angular momentum for the large-uncertainty intelligent states we compare exact solutions with analytical approximations in two limiting cases

  6. Efficient evaluation of angular power spectra and bispectra

    Science.gov (United States)

    Assassi, Valentin; Simonović, Marko; Zaldarriaga, Matias

    2017-11-01

    Angular statistics of cosmological observables are hard to compute. The main difficulty is due to the presence of highly-oscillatory Bessel functions which need to be integrated over. In this paper, we provide a simple and fast method to compute the angular power spectrum and bispectrum of any observable. The method is based on using an FFTlog algorithm to decompose the momentum-space statistics onto a basis of power-law functions. For each power law, the integrals over Bessel functions have a simple analytical solution. This allows us to efficiently evaluate these integrals, independently of the value of the multipole l. In particular, this method significantly speeds up the evaluation of the angular bispectrum compared to existing methods. To illustrate our algorithm, we compute the galaxy, lensing and CMB temperature angular power spectrum and bispectrum.

  7. The decay of orbital angular momentum entanglement in atmospheric turbulence

    CSIR Research Space (South Africa)

    Roux, FS

    2013-07-01

    Full Text Available Salam International Centre for Theoretical Physics, Trieste, Italy, 8-12 July 2013 The decay of orbital angular momentum entanglement in atmospheric turbulence Roux FS CSIR, National Laser Centre, Pretoria, 0001 Corresponding email: FSroux...

  8. Pluto Moons exhibit Orbital Angular Momentum Quantization per Mass

    Directory of Open Access Journals (Sweden)

    Potter F.

    2012-10-01

    Full Text Available The Pluto satellite system of the planet plus five moons is shown to obey the quan- tum celestial mechanics (QCM angular momentum per mass quantization condition predicted for any gravitationally bound system.

  9. Design and Implementation of a Digital Angular Rate Sensor

    Directory of Open Access Journals (Sweden)

    Zhen Peng

    2010-10-01

    Full Text Available With the aim of detecting the attitude of a rotating carrier, the paper presents a novel, digital angular rate sensor. The sensor consists of micro-sensing elements (gyroscope and accelerometer, signal processing circuit and micro-processor (DSP2812. The sensor has the feature of detecting three angular rates of a rotating carrier at the same time. The key techniques of the sensor, including sensing construction, sensing principles, and signal processing circuit design are presented. The test results show that the sensor can sense rolling, pitch and yaw angular rate at the same time and the measurement error of yaw (or pitch angular rate and rolling rate of the rotating carrier is less than 0.5%.

  10. About the velocity operator for spinning particles in quantum mechanics

    International Nuclear Information System (INIS)

    Salesi, Giovanni; Recami, Erasmo; Rodrigues Junior, Waldyr A.

    1995-12-01

    Starting from the formal expressions of the hydrodynamical (or local) quantities employed in the applications of Clifford Algebras to quantum mechanics, we introduce - in terms of the ordinary tensorial framework - a new definition for the field of a generic quantity. By translating from Clifford into sensor algebra, we also propose a new (non-relativistic) velocity operator for a spin 1/2 particle. This operator is the sum of the ordinary part p/m describing the mean motion (the motion of the center-of-mass), and of a second part associated with the so-called Zitterbewegung, which is the spin internal motion observed in the center-of-mass frame. This spin component of the velocity operator is non-zero not only in the Pauli theoretical framework in presence of external magnetic fields and spin precession, but also in the Schroedinger case, when the wave-function is a spin eigenstate. In the latter case, one gets a decomposition of the velocity field for the Madelueng fluid into two distinct parts: which constitutes the non-relativistic analogue of the Gordon decomposition for the Dirac current. We find furthermore that the Zitterbewegung motion involves a velocity field which is solenoidal, and that the local angular velocity is parallel to the spin vector. In presence of a non-constant spin vector (Pauli case) we have, besides the component normal to spin present even in the Schroedinger theory, also a component of the local velocity which is parallel to the rotor of the spin vector. (author). 19 refs

  11. A Very Fast and Angular Momentum Conserving Tree Code

    Energy Technology Data Exchange (ETDEWEB)

    Marcello, Dominic C., E-mail: dmarce504@gmail.com [Department of Physics and Astronomy, and Center for Computation and Technology Louisiana State University, Baton Rouge, LA 70803 (United States)

    2017-09-01

    There are many methods used to compute the classical gravitational field in astrophysical simulation codes. With the exception of the typically impractical method of direct computation, none ensure conservation of angular momentum to machine precision. Under uniform time-stepping, the Cartesian fast multipole method of Dehnen (also known as the very fast tree code) conserves linear momentum to machine precision. We show that it is possible to modify this method in a way that conserves both angular and linear momenta.

  12. Single crystal analyser accepting the narrowest neutron angular profile

    International Nuclear Information System (INIS)

    Abbas, Sohrab; Wagh, Apoorva G.; Strobl, Markus; Treimer, Wolfgang

    2007-01-01

    We have designed, fabricated and tested a novel silicon single crystal analyser. It accepts a 0.21 arcsec (FWHM) wide angular profile of a monochromatic 5.24 A neutron beam, in agreement with its design. This is the narrowest and sharpest acceptance angular profile attained to date in the world with a neutron analyser. This analyser will facilitate SUSANS experiments probing wave vector transfers Q ∼ 10 -6 A -1 . (author)

  13. Gamma-gamma angular correlation measurement in the 100 Ru

    International Nuclear Information System (INIS)

    Kenchian, G.

    1990-01-01

    An angular correlation automatic spectrometer with two Ge(Li) detectors has been developed. The spectrometer moves automatically, controlled by a microcomputer. The gamma-gamma directional angular correlations of coincidence transitions have been measured in 100 Ru nuclide, following the β + and electron capture of 100 Rh. The 100 Rh source has been produced with 100 Ru(p,n) 100 Rh reaction, using the proton beam of the Cyclotron Accelerator insiding in 100 Ru isotope. (author)

  14. A Very Fast and Angular Momentum Conserving Tree Code

    International Nuclear Information System (INIS)

    Marcello, Dominic C.

    2017-01-01

    There are many methods used to compute the classical gravitational field in astrophysical simulation codes. With the exception of the typically impractical method of direct computation, none ensure conservation of angular momentum to machine precision. Under uniform time-stepping, the Cartesian fast multipole method of Dehnen (also known as the very fast tree code) conserves linear momentum to machine precision. We show that it is possible to modify this method in a way that conserves both angular and linear momenta.

  15. Measurement of anisotropy in the cosmic background radiation on a large angular scale at 33 GHz

    International Nuclear Information System (INIS)

    Gorenstein, M.V.

    1978-11-01

    Results of a measurement of anisotropy in the 3 0 K cosmic background radiation on a large-angular-scale are presented. Observations were carried out with a dual-antenna microwave radiometer operating at 33 GHz (0.89 cm wavelength) flown on board a U-2 aircraft to 20-km altitude. In eleven flights, between December 1976 and May 1978, the radiometer measured differential intensity between pairs of directions distributed over most of the northern celestial hemisphere with an rms sensitivity of +- 46m 0 K/√Hz. The measurements show clear evidence of anisotropy that is readily interpreted as due to the motion of the earth relative to the sources of the radiation; the anisotropy is well fit by a cosine distribution of amplitude 3.61 +- 0.54 millireverse arrowreverse arrow-degrees Kelvin (m 0 K), one part in 800 of 3 0 K, implying a velocity of 361 +- 54 km/sec toward the direction 11.23 +- 0.46 hours right ascension, and 19.0 +- 7.5 0 declination. A simultaneous fit to a combined hypothesis of dipole (cos theta) and quadrupole (cos 2 theta) angular distributions places a 1 m 0 K limit on the amplitude of most components of quadruple anisotropy with 90% confidence. Additional analysis places a 0.5 m 0 K limit on uncorrelated fluctuations (sky-roughness) in the 3 0 K background on an angular scale of the antenna beam width, about 7 0 . This thesis describes the equipment development through three engineering flights and the data acquisition in eleven additional flights. The astrophysical results are then presented from the statistical analysis of the reduced data

  16. Angular Momentum in Disk Wind Revealed in the Young Star MWC 349A

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qizhou; Claus, Brian; Watson, Linda; Moran, James, E-mail: qzhang@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138 (United States)

    2017-03-01

    Disk winds are thought to play a critical role in star birth. As winds extract excess angular momentum from accretion disks, matter in the disk can be transported inward to the star to fuel mass growth. However, observational evidence of wind carrying angular momentum has been very limited. We present Submillimeter Array (SMA) observations of the young star MWC 349A in the H26 α and H30 α recombination lines. The high signal-to-noise ratios made possible by the maser emission process allow us to constrain the relative astrometry of the maser spots to milli-arcsecond precision. Previous observations of the H30 α line with the SMA and the Plateau de Bure interferometer (PdBI) showed that masers are distributed in the disk and wind. Our new high-resolution observations of the H26 α line reveal differences in spatial distribution from that of the H30 α line. H26 α line masers in the disk are excited in a thin annulus with a radius of about 25 au, while the H30 α line masers are formed in a slightly larger annulus with a radius of 30 au. This is consistent with expectations for maser excitation in the presence of an electron density variation of approximately R {sup −4}. In addition, the H30 α and H26 α line masers arise from different parts in the wind. This difference is also expected from maser theory. The wind component of both masers exhibits line-of-sight velocities that closely follow a Keplerian law. This result provides strong evidence that the disk wind extracts significant angular momentum, thereby facilitating mass accretion in the young star.

  17. The Angular Momentum of Baryons and Dark Matter Halos Revisited

    Science.gov (United States)

    Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated

  18. A sensitive search for molecular gas in high-velocity clouds

    NARCIS (Netherlands)

    Wakker, BP; Murphy, EM; VanWoerden, H; Dame, TM

    1997-01-01

    We report on observations of the J = 1-0 line of (CO)-C-12 at 115 GH, toward several high-velocity H I clouds (HVCs). High angular resolution observations at 21 cm show the presence of dense cores with N(H I) = (2-4) x 10(20) cm(-2) and n(H I) = 30-800(kpc)(-1) cm(-3). We observed the CO line toward

  19. Radial profiles of velocity and pressure for condensation-induced hurricanes

    International Nuclear Information System (INIS)

    Makarieva, A.M.; Gorshkov, V.G.

    2011-01-01

    The Bernoulli integral in the form of an algebraic equation is obtained for the hurricane air flow as the sum of the kinetic energy of wind and the condensational potential energy. With an account for the eye rotation energy and the decrease of angular momentum towards the hurricane center it is shown that the theoretical profiles of pressure and velocity agree well with observations for intense hurricanes. The previous order of magnitude estimates obtained in pole approximation are confirmed.

  20. The multiplicity of massive stars: A high angular resolution survey with the HST fine guidance sensor

    International Nuclear Information System (INIS)

    Aldoretta, E. J.; Gies, D. R.; Henry, T. J.; Jao, W.-C.; Norris, R. P.

    2015-01-01

    We present the results of an all-sky survey made with the Fine Guidance Sensor on the Hubble Space Telescope to search for angularly resolved binary systems among massive stars. The sample of 224 stars is comprised mainly of Galactic O- and B-type stars and luminous blue variables, plus a few luminous stars in the Large Magellanic Cloud. The FGS TRANS mode observations are sensitive to the detection of companions with an angular separation between 0.″01 and 1.″0 and brighter than △m=5. The FGS observations resolved 52 binary and 6 triple star systems and detected partially resolved binaries in 7 additional targets (43 of these are new detections). These numbers yield a companion detection frequency of 29% for the FGS survey. We also gathered literature results on the numbers of close spectroscopic binaries and wider astrometric binaries among the sample, and we present estimates of the frequency of multiple systems and the companion frequency for subsets of stars residing in clusters and associations, field stars, and runaway stars. These results confirm the high multiplicity fraction, especially among massive stars in clusters and associations. We show that the period distribution is approximately flat in increments of logP. We identify a number of systems of potential interest for long-term orbital determinations, and we note the importance of some of these companions for the interpretation of the radial velocities and light curves of close binaries that have third companions.

  1. Angular momentum transfer in primordial discs and the rotation of the first stars

    Science.gov (United States)

    Hirano, Shingo; Bromm, Volker

    2018-02-01

    We investigate the rotation velocity of the first stars by modelling the angular momentum transfer in the primordial accretion disc. Assessing the impact of magnetic braking, we consider the transition in angular momentum transport mode at the Alfvén radius, from the dynamically dominated free-fall accretion to the magnetically dominated solid-body one. The accreting protostar at the centre of the primordial star-forming cloud rotates with close to breakup speed in the case without magnetic fields. Considering a physically-motivated model for small-scale turbulent dynamo amplification, we find that stellar rotation speed quickly declines if a large fraction of the initial turbulent energy is converted to magnetic energy (≳ 0.14). Alternatively, if the dynamo process were inefficient, for amplification due to flux-freezing, stars would become slow rotators if the pre-galactic magnetic field strength is above a critical value, ≃ 10-8.2 G, evaluated at a scale of nH = 1 cm-3, which is significantly higher than plausible cosmological seed values (˜10-15 G). Because of the rapid decline of the stellar rotational speed over a narrow range in model parameters, the first stars encounter a bimodal fate: rapid rotation at almost the breakup level, or the near absence of any rotation.

  2. Angular momentum transfer in primordial discs and the rotation of the first stars

    Science.gov (United States)

    Hirano, Shingo; Bromm, Volker

    2018-05-01

    We investigate the rotation velocity of the first stars by modelling the angular momentum transfer in the primordial accretion disc. Assessing the impact of magnetic braking, we consider the transition in angular momentum transport mode at the Alfvén radius, from the dynamically dominated free-fall accretion to the magnetically dominated solid-body one. The accreting protostar at the centre of the primordial star-forming cloud rotates with close to breakup speed in the case without magnetic fields. Considering a physically motivated model for small-scale turbulent dynamo amplification, we find that stellar rotation speed quickly declines if a large fraction of the initial turbulent energy is converted to magnetic energy (≳ 0.14). Alternatively, if the dynamo process were inefficient, for amplification due to flux freezing, stars would become slow rotators if the pre-galactic magnetic field strength is above a critical value, ≃10-8.2 G, evaluated at a scale of nH = 1 cm-3, which is significantly higher than plausible cosmological seed values (˜10-15 G). Because of the rapid decline of the stellar rotational speed over a narrow range in model parameters, the first stars encounter a bimodal fate: rapid rotation at almost the breakup level, or the near absence of any rotation.

  3. Calculation of photodetachment cross sections and photoelectron angular distributions of negative ions using density functional theory.

    Science.gov (United States)

    Liu, Yuan; Ning, Chuangang

    2015-10-14

    Recently, the development of photoelectron velocity map imaging makes it much easier to obtain the photoelectron angular distributions (PADs) experimentally. However, explanations of PADs are only qualitative in most cases, and very limited works have been reported on how to calculate PAD of anions. In the present work, we report a method using the density-functional-theory Kohn-Sham orbitals to calculate the photodetachment cross sections and the anisotropy parameter β. The spherical average over all random molecular orientation is calculated analytically. A program which can handle both the Gaussian type orbital and the Slater type orbital has been coded. The testing calculations on Li(-), C(-), O(-), F(-), CH(-), OH(-), NH2 (-), O2 (-), and S2 (-) show that our method is an efficient way to calculate the photodetachment cross section and anisotropy parameter β for anions, thus promising for large systems.

  4. Settling velocities in batch sedimentation

    International Nuclear Information System (INIS)

    Fricke, A.M.; Thompson, B.E.

    1982-10-01

    The sedimentation of mixtures containing one and two sizes of spherical particles (44 and 62 μm in diameter) was studied. Radioactive tracing with 57 Co was used to measure the settling velocities. The ratio of the settling velocity U of uniformly sized particles to the velocity predicted to Stokes' law U 0 was correlated to an expression of the form U/U 0 = epsilon/sup α/, where epsilon is the liquid volume fraction and α is an empirical constant, determined experimentally to be 4.85. No effect of viscosity on the ratio U/U 0 was observed as the viscosity of the liquid medium was varied from 1x10 -3 to 5x10 -3 Pa.s. The settling velocities of particles in a bimodal mixture were fit by the same correlation; the ratio U/U 0 was independent of the concentrations of different-sized particles

  5. Comparison between length and velocity gauges in quantum simulations of high-order harmonic generation

    DEFF Research Database (Denmark)

    Han, Yong-Chang; Madsen, Lars Bojer

    2010-01-01

    , and acceleration forms, and two gauges, the length and velocity gauges. The relationships among the harmonic phases obtained from the Fourier transform of the three forms are discussed in detail. Although quantum mechanics is gauge invariant and the length and velocity gauges should give identical results, the two...... gauges present different computation efficiencies, which reflects the different behavior in terms of characteristics of the physical couplings acting in the two gauges. In order to obtain convergence, more angular momentum states are required in the length gauge, while more grid points are required...

  6. Velocity and Motion Control of a Self-Balancing Vehicle Based on a Cascade Control Strategy

    Directory of Open Access Journals (Sweden)

    Miguel Velazquez

    2016-06-01

    Full Text Available This paper presents balancing, velocity and motion control of a self-balancing vehicle. A cascade controller is implemented for both balancing control and angular velocity control. This controller is tested in simulations using a proposed mathematical model of the system. Motion control is achieved based on the kinematics of the robot. Control hardware is designed and integrated to implement the proposed controllers. Pitch is kept under 1° from the equilibrium position with no external disturbances. The linear cascade control is able to handle slight changes in the system dynamics, such as in the centre of mass and the slope on an inclined surface.

  7. Isotropic gates and large gamma detector arrays versus angular distributions

    International Nuclear Information System (INIS)

    Iacob, V.E.; Duchene, G.

    1997-01-01

    Angular information extracted from in-beam γ ray measurements are of great importance for γ ray multipolarity and nuclear spin assignments. In our days large Ge detector arrays became available allowing the measurements of extremely weak γ rays in almost 4π sr solid angle (e.g., EUROGAM detector array). Given the high detector efficiency it is common for the mean suppressed coincidence multiplicity to reach values as high as 4 to 6. Thus, it is possible to gate on particular γ rays in order to enhance the relative statistics of a definite reaction channel and/or a definite decaying path in the level scheme of the selected residual nucleus. As compared to angular correlations, the conditioned angular distribution spectra exhibit larger statistics because in the latter the gate-setting γ ray may be observed by all the detectors in the array, relaxing somehow the geometrical restrictions of the angular correlations. Since the in-beam γ ray emission is anisotropic one could inquire that gate setting as mentioned above, based on anisotropic γ ray which would perturb the angular distributions in the unfolded events. As our work proved, there is no reason to worry about this if the energy gate runs over the whole solid angle in an ideal 4π sr detector, i.e., if the gate is isotropic. In real quasi 4π sr detector arrays the corresponding quasi isotropic gate preserves the angular properties of the unfolded data, too. However extraction of precise angular distribution coefficient especially a 4 , requires the consideration of the deviation of the quasi isotropic gate relative to the (ideal) isotropic gate

  8. Smoothed dissipative particle dynamics with angular momentum conservation

    International Nuclear Information System (INIS)

    Müller, Kathrin; Fedosov, Dmitry A.; Gompper, Gerhard

    2015-01-01

    Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier–Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor–Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential

  9. Initial angular momentum and flow in high energy nuclear collisions

    Science.gov (United States)

    Fries, Rainer J.; Chen, Guangyao; Somanathan, Sidharth

    2018-03-01

    We study the transfer of angular momentum in high energy nuclear collisions from the colliding nuclei to the region around midrapidity, using the classical approximation of the color glass condensate (CGC) picture. We find that the angular momentum shortly after the collision (up to times ˜1 /Qs , where Qs is the saturation scale) is carried by the "β -type" flow of the initial classical gluon field, introduced by some of us earlier. βi˜μ1∇iμ2-μ2∇iμ1 (i =1 ,2 ) describes the rapidity-odd transverse energy flow and emerges from Gauss's law for gluon fields. Here μ1 and μ2 are the averaged color charge fluctuation densities in the two nuclei, respectively. Interestingly, strong coupling calculations using anti-de Sitter/conformal field theory (AdS/CFT) techniques also find an energy flow term featuring this particular combination of nuclear densities. In classical CGC the order of magnitude of the initial angular momentum per rapidity in the reaction plane, at a time 1 /Qs , is |d L2/d η |≈ RAQs-3ɛ¯0/2 at midrapidity, where RA is the nuclear radius, and ɛ¯0 is the average initial energy density. This result emerges as a cancellation between a vortex of energy flow in the reaction plane aligned with the total angular momentum, and energy shear flow opposed to it. We discuss in detail the process of matching classical Yang-Mills results to fluid dynamics. We will argue that dissipative corrections should not be discarded to ensure that macroscopic conservation laws, e.g., for angular momentum, hold. Viscous fluid dynamics tends to dissipate the shear flow contribution that carries angular momentum in boost-invariant fluid systems. This leads to small residual angular momentum around midrapidity at late times for collisions at high energies.

  10. Smoothed dissipative particle dynamics with angular momentum conservation

    Energy Technology Data Exchange (ETDEWEB)

    Müller, Kathrin, E-mail: k.mueller@fz-juelich.de; Fedosov, Dmitry A., E-mail: d.fedosov@fz-juelich.de; Gompper, Gerhard, E-mail: g.gompper@fz-juelich.de

    2015-01-15

    Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier–Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor–Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.

  11. Online Wavelet Complementary velocity Estimator.

    Science.gov (United States)

    Righettini, Paolo; Strada, Roberto; KhademOlama, Ehsan; Valilou, Shirin

    2018-02-01

    In this paper, we have proposed a new online Wavelet Complementary velocity Estimator (WCE) over position and acceleration data gathered from an electro hydraulic servo shaking table. This is a batch estimator type that is based on the wavelet filter banks which extract the high and low resolution of data. The proposed complementary estimator combines these two resolutions of velocities which acquired from numerical differentiation and integration of the position and acceleration sensors by considering a fixed moving horizon window as input to wavelet filter. Because of using wavelet filters, it can be implemented in a parallel procedure. By this method the numerical velocity is estimated without having high noise of differentiators, integration drifting bias and with less delay which is suitable for active vibration control in high precision Mechatronics systems by Direct Velocity Feedback (DVF) methods. This method allows us to make velocity sensors with less mechanically moving parts which makes it suitable for fast miniature structures. We have compared this method with Kalman and Butterworth filters over stability, delay and benchmarked them by their long time velocity integration for getting back the initial position data. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Velocity evolution of galaxy clustering

    Energy Technology Data Exchange (ETDEWEB)

    Saslaw, W.C.; Aarseth, S.J.

    1982-02-15

    We have examined the changing velocity distribution of galaxies as they cluster in computer models of the expanding universe. The models are 4000-body numerical simulations of galaxies with a large range of masses interacting gravitationally. Clustering in velocity space is measured by calculating the residual peculiar velocities around the Hubble expansion. These form ''Hubble streaks as clustering progresses. We distinguish isolated field galaxies from clustered galaxies. In contrast to the usual belief, the velocity dispersion of the most extreme field galaxies does not decrease adiabatically. Rather, it is dominated by the perturbations of distant large clusters as they form and it decreases much more slowly than the inverse expansion length scale, R/sup -1/. The velocity dispersion of extreme field galaxies is a good cosmological indicator of ..cap omega.. = rho/rho/sub crit/. Preliminary comparison of several simulations with observtions shows that our universe agrees better with low density models, ..cap omega..< or =0.1. The velocity dispersion of cluster centers of mass is a good cosmological marker as well. We also suggest another new method for estimating ..cap omega.., based on the history of extreme field galaxies.

  13. Velocity of isokinetic trunk exercises influences back muscle recruitment patterns in healthy subjects.

    Science.gov (United States)

    Van Damme, Benedicte B L; Stevens, Veerle K; Van Tiggelen, Damien E; Duvigneaud, Nathalie N P; Neyens, Ellen; Danneels, Lieven A

    2013-04-01

    Isokinetic exercises at different angular velocities on Cybex devices are often used for assessment and therapy in chronic low back pain patients. Little is known about the effect of velocity of movement on the muscle activity during these exercises. The purpose of this study was to investigate both relative muscle activity and ratios of local to global muscle activity at the different velocities of isokinetic movements on a Cybex dynamometer. Fifty-three healthy employees of Belgian Defence (26 male and 27 female) aged between 20 and 57 years old voluntarily performed isometric and isokinetic exercises at four different velocities. Surface electromyographic signals of different abdominal and back muscles were recorded on both sides. Both the relative muscle activity and the local to global muscle activity ratio of the back muscles were affected by changes in velocities of isokinetic exercises. The global muscle system was more influenced by changes in velocity, than the local muscle system. Abdominal relative muscle activity and ratios were not influenced by velocity of movement. This study revealed that the velocity of isokinetic extension exercises influences the recruitment of the back muscles, meaning that protocols of training programs should be adapted in function of the focus of the therapy. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Effects of stimulus size and velocity on steady-state smooth pursuit induced by realistic images

    Science.gov (United States)

    Li, Feng; Pelz, Jeff B.; Daly, Scott J.

    2010-02-01

    Smooth pursuit eye movements align the retina with moving targets, ideally stabilizing the retinal image. At a steadystate, eye movements typically reach an approximately constant velocity which depends on, and is usually lower than the target velocity. Experiment 1 investigated the effect of target size and velocity on smooth pursuit induced by realistic images (color photographs of an apple and flower subtending 2° and 17°, respectively), in comparison with a small dot subtending a fraction of a degree. The extended stimuli were found to enhance smooth pursuit gain. Experiment 2 examined the absolute velocity limit of smooth pursuit elicited by the small dot and the effect of the extended targets on the velocity limit. The eye velocity for tracking the dot was found to be saturated at about 63 deg/sec while the saturation velocity occurred at higher velocities for the extended images. The difference in gain due to target size was significant between dot and the two extended stimuli, while no statistical difference exists between an apple and flower stimuli of wider angular extent. Detailed knowledge of the smooth pursuit eye movements is important for several areas of electronic imaging, in particular, assessing perceived motion blur of displayed objects.

  15. Determination of Anisotropic Ion Velocity Distribution Function in Intrinsic Gas Plasma. Theory.

    Science.gov (United States)

    Mustafaev, A.; Grabovskiy, A.; Murillo, O.; Soukhomlinov, V.

    2018-02-01

    The first seven coefficients of the expansion of the energy and angular distribution functions in Legendre polynomials for Hg+ ions in Hg vapor plasma with the parameter E/P ≈ 400 V/(cm Torr) are measured for the first time using a planar one-sided probe. The analytic solution to the Boltzmann kinetic equation for ions in the plasma of their parent gas is obtained in the conditions when the resonant charge exchange is the predominant process, and ions acquire on their mean free path a velocity much higher than the characteristic velocity of thermal motion of atoms. The presence of an ambipolar field of an arbitrary strength is taken into account. It is shown that the ion velocity distribution function is determined by two parameters and differs substantially from the Maxwellian distribution. Comparison of the results of calculation of the drift velocity of He+ ions in He, Ar+ in Ar, and Hg+ in Hg with the available experimental data shows their conformity. The results of the calculation of the ion distribution function correctly describe the experimental data obtained from its measurement. Analysis of the result shows that in spite of the presence of the strong field, the ion velocity distribution functions are isotropic for ion velocities lower than the average thermal velocity of atoms. With increasing ion velocity, the distribution becomes more and more extended in the direction of the electric field.

  16. Velocity distribution in snow avalanches

    Science.gov (United States)

    Nishimura, K.; Ito, Y.

    1997-12-01

    In order to investigate the detailed structure of snow avalanches, we have made snow flow experiments at the Miyanomori ski jump in Sapporo and systematic observations in the Shiai-dani, Kurobe Canyon. In the winter of 1995-1996, a new device to measure static pressures was used to estimate velocities in the snow cloud that develops above the flowing layer of avalanches. Measurements during a large avalanche in the Shiai-dani which damaged and destroyed some instruments indicate velocities increased rapidly to more than 50 m/s soon after the front. Velocities decreased gradually in the following 10 s. Velocities of the lower flowing layer were also calculated by differencing measurement of impact pressure. Both recordings in the snow cloud and in the flowing layer changed with a similar trend and suggest a close interaction between the two layers. In addition, the velocity showed a periodic change. Power spectrum analysis of the impact pressure and the static pressure depression showed a strong peak at a frequency between 4 and 6 Hz, which might imply the existence of either ordered structure or a series of surges in the flow.

  17. Characteristic evolutions in numerical relativity using six angular patches

    International Nuclear Information System (INIS)

    Reisswig, Christian; Bishop, Nigel T; Lai, Chi Wai; Thornburg, Jonathan; Szilagyi, Bela

    2007-01-01

    The characteristic approach to numerical relativity is a useful tool in evolving gravitational systems. In the past this has been implemented using two patches of stereographic angular coordinates. In other applications, a six-patch angular coordinate system has proved effective. Here we investigate the use of a six-patch system in characteristic numerical relativity, by comparing an existing two-patch implementation (using second-order finite differencing throughout) with a new six-patch implementation (using either second- or fourth-order finite differencing for the angular derivatives). We compare these different codes by monitoring the Einstein constraint equations, numerically evaluated independently from the evolution. We find that, compared to the (second-order) two-patch code at equivalent resolutions, the errors of the second-order six-patch code are smaller by a factor of about 2, and the errors of the fourth-order six-patch code are smaller by a factor of nearly 50

  18. Orbital Angular Momentum Multiplexing over Visible Light Communication Systems

    Science.gov (United States)

    Tripathi, Hardik Rameshchandra

    This thesis proposes and explores the possibility of using Orbital Angular Momentum multiplexing in Visible Light Communication system. Orbital Angular Momentum is mainly applied for laser and optical fiber transmissions, while Visible Light Communication is a technology using the light as a carrier for wireless communication. In this research, the study of the state of art and experiments showing some results on multiplexing based on Orbital Angular Momentum over Visible Light Communication system were done. After completion of the initial stage; research work and simulations were performed on spatial multiplexing over Li-Fi channel modeling. Simulation scenarios which allowed to evaluate the Signal-to-Noise Ratio, Received Power Distribution, Intensity and Illuminance were defined and developed.

  19. Nuclear level density variation with angular momentum induced shape transition

    International Nuclear Information System (INIS)

    Aggarwal, Mamta

    2016-01-01

    Variation of Nuclear level density (NLD) with the excitation energy and angular momentum in particular has been a topic of interest in the recent past and there have been continuous efforts in this direction on the theoretical and experimental fronts but a conclusive trend in the variation of nuclear level density parameter with angular momentum has not been achieved so far. A comprehensive investigation of N=68 isotones around the compound nucleus 119 Sb from neutron rich 112 Ru (Z=44) to neutron deficient 127 Pr (Z= 59) nuclei is presented to understand the angular momentum induced variations in inverse level density parameter and the possible influence of deformation and structural transitions on the variations on NLd

  20. Angular trapping of anisometric nano-objects in a fluid.

    Science.gov (United States)

    Celebrano, Michele; Rosman, Christina; Sönnichsen, Carsten; Krishnan, Madhavi

    2012-11-14

    We demonstrate the ability to trap, levitate, and orient single anisometric nanoscale objects with high angular precision in a fluid. An electrostatic fluidic trap confines a spherical object at a spatial location defined by the minimum of the electrostatic system free energy. For an anisometric object and a potential well lacking angular symmetry, the system free energy can further strongly depend on the object's orientation in the trap. Engineering the morphology of the trap thus enables precise spatial and angular confinement of a single levitating nano-object, and the process can be massively parallelized. Since the physics of the trap depends strongly on the surface charge of the object, the method is insensitive to the object's dielectric function. Furthermore, levitation of the assembled objects renders them amenable to individual manipulation using externally applied optical, electrical, or hydrodynamic fields, raising prospects for reconfigurable chip-based nano-object assemblies.

  1. ANGULAR LIGHT-SCATTERING STUDIES ON ISOLATED MITOCHONDRIA

    Science.gov (United States)

    Gotterer, Gerald S.; Thompson, Thomas E.; Lehninger, Albert L.

    1961-01-01

    Angular light-scattering studies have been carried out on suspensions of isolated rat liver mitochondria. The angular scatter pattern has a large forward component, typical of large particles. Changes in dissymmetry and in the intensity of light scattered at 90° have been correlated with changes in optical density during the course of mitochondrial swelling and contraction. Such changes can be measured at mitochondrial concentrations much below those required for optical density measurements. Changes in mitochondrial geometry caused by factors "leaking" from mitochondria, not detectable by optical density measurements, have been demonstrated by measuring changes in dissymmetry. Angular light-scattering measurements therefore offer the advantages of increased sensitivity and of added indices of changes in mitochondrial conformation. PMID:19866589

  2. Angular momentum dependence of the nuclear level density parameter

    Directory of Open Access Journals (Sweden)

    Gohil M.

    2014-03-01

    Full Text Available Neutron evaporation spectra alongwith γ-multiplicity has been measured from the 185Re* compound nucleus at the excitation energies ~27 and 37 MeV. Statistical model analysis of the experimental data has been carried out to extract the value of the inverse level density parameter k at different angular momentum regions (J corresponding to different γ-multiplicity. It is observed that, for the present system the value of k remains almost constant for different J. The present results on the angular momentum dependence of the nuclear level density (NLD parameter ã (=A/k, for nuclei with A ~180 is quite different from our earlier measurements in case of light and medium mass systems. The present analysis provides useful information to understand the angular momentum dependence of NLD at different nuclear mass regions.

  3. Angular Magnetoresistance of Nanowires with Alternating Cobalt and Nickel Segments

    KAUST Repository

    Mohammed, Hanan

    2017-06-22

    Magnetization reversal in segmented Co/Ni nanowires with varying number of segments was studied using angular Magnetoresistance (MR) measurements on isolated nanowires. The MR measurements offer an insight into the pinning of domain walls within the nanowires. Angular MR measurements were performed on nanowires with two and multiple segments by varying the angle between the applied magnetic field and nanowire (−90° ≤θ≤90°). The angular MR measurements reveal that at lower values of θ the switching fields are nearly identical for the multisegmented and two-segmented nanowires, whereas at higher values of θ, a decrease in the switching field is observed in the case of two segmented nanowires. The two segmented nanowires generally exhibit a single domain wall pinning event, whereas an increased number of pinning events are characteristic of the multisegmented nanowires at higher values of θ. In-situ magnetic force microscopy substantiates reversal by domain wall nucleation and propagation in multisegmented nanowires.

  4. Spin and orbital angular momentum distribution functions of the nucleon

    Science.gov (United States)

    Wakamatsu, M.; Watabe, T.

    2000-09-01

    A theoretical prediction is given for the spin and orbital angular momentum distribution functions of the nucleon within the framework of an effective quark model of QCD, i.e., the chiral quark soliton model. An outstanding feature of the model is that it predicts a fairly small quark spin fraction of the nucleon ΔΣ~=0.35, which in turn dictates that the remaining 65% of the nucleon spin is carried by the orbital angular momentum of quarks and antiquarks at the model energy scale of Q2~=0.3 GeV2. This large orbital angular momentum necessarily affects the scenario of scale dependence of the nucleon spin contents in a drastic way.

  5. Microbeam High Angular Resolution Diffraction Applied to Optoelectronic Devices

    International Nuclear Information System (INIS)

    Kazimirov, A.; Bilderback, D. H.; Sirenko, A. A.; Cai, Z.-H.; Lai, B.

    2007-01-01

    Collimating perfect crystal optics in a combination with the X-ray focusing optics has been applied to perform high angular resolution microbeam diffraction and scattering experiments on micron-size optoelectronic devices produced by modern semiconductor technology. At CHESS, we used capillary optics and perfect Si/Ge crystal(s) arrangement to perform X-ray standing waves, high angular-resolution diffraction and high resolution reciprocal space mapping analysis. At the APS, 2ID-D microscope beamline, we employed a phase zone plate producing a beam with the size of 240 nm in the horizontal plane and 350 nm in the vertical (diffraction) plane and a perfect Si (004) analyzer crystal to perform diffraction analysis of selectively grown InGaAsP and InGaAlAs-based waveguides with arc sec angular resolution

  6. Angular momentum non-conserving symmetries in bosonic models

    Energy Technology Data Exchange (ETDEWEB)

    Fortunato, L [ECT, Strada delle Tabarelle 286, I-38123 Villazzano (Trento) (Italy); De Graaf, W A, E-mail: fortunat@pd.infn.it [Dip. Matematica, Universita di Trento, via Sommarive 24, I-38123 Povo, Trento (Italy)

    2011-04-08

    The Levi-Malcev decomposition is applied to bosonic models of quantum mechanics based on unitary Lie algebras u(2), u(2)+u(2), u(3) and u(4) to clearly disentangle semisimple subalgebras. The theory of weighted Dynkin diagrams is then applied to identify conjugacy classes of relevant A{sub 1} subalgebras allowing us to introduce a complete classification of new angular momentum non conserving (AMNC) dynamical symmetries. The tensor analysis of the whole algebra based on the new 'angular momentum' operators reveals unexpected spinors to occur in purely bosonic models. The new chains of subalgebra can be invoked to set up ANMC bases for diagonalization.

  7. Angular momentum non-conserving symmetries in bosonic models

    Science.gov (United States)

    Fortunato, L.; de Graaf, W. A.

    2011-04-01

    The Levi-Malcev decomposition is applied to bosonic models of quantum mechanics based on unitary Lie algebras u(2), u(2)⊕u(2), u(3) and u(4) to clearly disentangle semisimple subalgebras. The theory of weighted Dynkin diagrams is then applied to identify conjugacy classes of relevant A1 subalgebras allowing us to introduce a complete classification of new angular momentum non conserving (AMNC) dynamical symmetries. The tensor analysis of the whole algebra based on the new 'angular momentum' operators reveals unexpected spinors to occur in purely bosonic models. The new chains of subalgebra can be invoked to set up ANMC bases for diagonalization.

  8. Spatial distribution of angular momentum inside the nucleon

    Science.gov (United States)

    Lorcé, Cédric; Mantovani, Luca; Pasquini, Barbara

    2018-01-01

    We discuss in detail the spatial distribution of angular momentum inside the nucleon. We show that the discrepancies between different definitions originate from terms that integrate to zero. Even though these terms can safely be dropped at the integrated level, they have to be taken into account when discussing distributions. Using the scalar diquark model, we illustrate our results and, for the first time, check explicitly that the equivalence between kinetic and canonical orbital angular momentum persists at the level of distributions, as expected in a system without gauge degrees of freedom.

  9. On angular distribution of nucleus fission fragments by fast neutrons

    International Nuclear Information System (INIS)

    Barabanov, A.L.; Grechukhin, D.P.

    1987-01-01

    Evaluation of amplitudes of quadrupole and hexadecapole components of angular distribution of nucleus fission fragments by neutrons with the energies E n < or approx. 6 MeV is conducted. Stability of this amplitude to permeability optical coefficient variations for neutrons is revealed. It is shown, that the ratio of these amplitudes as well as the character of their dependence on the target nucleus orientation degree are sensitive to the type of fission probability distribution along K projection if fissile nucleus J spin to the fragment scattering axis. This sensitivity may be used for fragment angular distribution anisotropy formation statistical model verification

  10. Radio source orientation and the angular diameter-redshift relation

    Science.gov (United States)

    Onuora, L. I.

    1991-08-01

    The effect of a nonrandom source orientation on the angular diameter-redshift relation was considered for the 3CR sample of Laing et al., based on the 'unified' scheme of Barthel. For an inhomogeneous sample of objects displaying milliarcsecond scale structure, it was found that there was no evidence for a systematic variation for orientation angle with redshift. However, if it was assumed that quasars are closer to the line of sight than powerful extended radio galaxies, then the observed angular size-redshift relation could be interpreted in terms of source orientation, rather than linear size evolution.

  11. Four Cases of Angular Cheilitis in Orthodontic Patients

    Directory of Open Access Journals (Sweden)

    P Kafaie

    2006-07-01

    Full Text Available Contact dermatitis is an inflammatory reaction of the skin and mucosa to either external or internal factors. It can be divided to two forms of irritant contact dermatitis and allergic contact dermatitis. Nickel is one of the most common materials that causes allergic contact dermatitis and is widely used in orthodontic appliances. The inflammatory reaction to this metal in orthodontics is usually stomatitis and angular cheilitis is very rare. We report 4 cases of angular cheilitis in orthodontic patients and discuss about their causes and treatments.

  12. Examples of Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Hansen, Peter M.; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    To measure blood flow velocity in vessels with conventional ultrasound, the velocity is estimated along the direction of the emitted ultrasound wave. It is therefore impossible to obtain accurate information on blood flow velocity and direction, when the angle between blood flow and ultrasound wave...... been tried including Transverse Oscillation. This method has been tested in computer simulations, on flow phantoms and in-vivo, and subsequently validated against MRI angiography. Transverse Oscillation is now implemented in a commercial ultrasound scanner from BK Medical (UltraView). In this article...... UltraView is demonstrated on the carotid artery, jugular vein and femoral vein that all runs almost parallel to the skin and thus is angled near 90° to the ultrasound waves. Arterial and venous simple and complex flow with formation of vortices is demonstrated by scanning on the longitudinal axis...

  13. Angle independent velocity spectrum determination

    DEFF Research Database (Denmark)

    2014-01-01

    An ultrasound imaging system (100) includes a transducer array (102) that emits an ultrasound beam and produces at least one transverse pulse-echo field that oscillates in a direction transverse to the emitted ultrasound beam and that receive echoes produced in response thereto and a spectral vel...... velocity estimator (110) that determines a velocity spectrum for flowing structure, which flows at an angle of 90 degrees and flows at angles less than 90 degrees with respect to the emitted ultrasound beam, based on the received echoes....

  14. What velocities and eccentricities tell us about radial migration

    Directory of Open Access Journals (Sweden)

    Schönrich R.

    2012-02-01

    Full Text Available This note attempts to interpret some of the recent findings about a downtrend in the mean azimuthal velocity of low [α/Fe] thin disc stars with increasing metallicity. The presence of such a trend was predicted in the model of [19], albeit with a slightly steeper slope. We show that in a simple picture a Galactic disc without mixing in angular momenta would display an exceedingly steep trend, while in the case of complete mixing of all stars the trend has to vanish. The difference between model and observational data can hence be interpreted as the consequence of the radial abundance gradient in the model being too high resulting in an underestimate of the migration strength. We shortly discuss the value of eccentricity distributions in constraining structure and history of the Galactic disc.

  15. Relationship between Lower Limb Angular Kinematic Variables and the Effectiveness of Sprinting during the Acceleration Phase

    Directory of Open Access Journals (Sweden)

    Artur Struzik

    2016-01-01

    Full Text Available The ability to reach a high running velocity over a short distance is essential to a high playing performance in team games. The aim of this study was to determine the relationship between running time over a 10-meter section of a 30-meter sprint along a straight line and changes in the angle and angular velocity that were observed in the ankle, knee, and hip joints. The possible presence may help to optimize motion efficiency during acceleration sprint phase. Eighteen girls involved in team sports were examined in the study. The Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using the Noraxon MyoMotion system. Statistically significant relationships were found between running time over a 10-meter section and the kinematic variables of hip and ankle joints. An excessively large flexion in hip joints might have an unfavorable effect on running time during the acceleration phase. Furthermore, in order to minimize running time during the acceleration phase, stride should be maintained along a line (a straight line rather than from side to side. It is also necessary to ensure an adequate range of motion in the hip and ankle joints with respect to the sagittal axis.

  16. Relationship between Lower Limb Angular Kinematic Variables and the Effectiveness of Sprinting during the Acceleration Phase.

    Science.gov (United States)

    Struzik, Artur; Konieczny, Grzegorz; Stawarz, Mateusz; Grzesik, Kamila; Winiarski, Sławomir; Rokita, Andrzej

    2016-01-01

    The ability to reach a high running velocity over a short distance is essential to a high playing performance in team games. The aim of this study was to determine the relationship between running time over a 10-meter section of a 30-meter sprint along a straight line and changes in the angle and angular velocity that were observed in the ankle, knee, and hip joints. The possible presence may help to optimize motion efficiency during acceleration sprint phase. Eighteen girls involved in team sports were examined in the study. The Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using the Noraxon MyoMotion system. Statistically significant relationships were found between running time over a 10-meter section and the kinematic variables of hip and ankle joints. An excessively large flexion in hip joints might have an unfavorable effect on running time during the acceleration phase. Furthermore, in order to minimize running time during the acceleration phase, stride should be maintained along a line (a straight line) rather than from side to side. It is also necessary to ensure an adequate range of motion in the hip and ankle joints with respect to the sagittal axis.

  17. Measurement and role of linear and angular momenta transferred in peripheral collisions Kr + Au and Kr + Th at 43 MeV/u

    International Nuclear Information System (INIS)

    Delaunay, F.

    1990-01-01

    In this experiment performed at GANIL, the use of the gaseous multidetectors DELF and XYZT allows the detection of the heavy fragments (Z ≥ 5) whose velocity is larger than 3 cm/ns when the emission angle is lower than 30 0 and whose velocity is larger than 0.5 cm/ns when the emission angle is greater than 30 0 . For the reactions Kr + Au and Kr + Th at 43 MeV/u, we have observed with a still significative occurrence, events where 6 fragments are produced and we have studied the events where at least 3 heavy fragments were detected. In order to separate the peripheral collisions from the central ones, a collective variable measuring the dispersion of the relative velocity between each couple of fragment is used for events where 3 or 4 heavy fragments are recorded. Afterwards, a selection method is presented for the peripheral events in order to deal only with almost complete events. The atomical number of the fragment whose velocity is nearly equal to the beam velocity, is used to estimate the impact parameter. We find that for a given impact parameter, some different mechanisms are present. A method of measurement of the angular momentum is elaborated from the angular distribution of the fission fragments. A study of incomplete linear momentum transfer leads to a transfer rate of about 40%. The angular momentum of the target like fragment just before fission is also small. The results of the abrasion-ablation model and of the two-step model are quite close to the experimental results [fr

  18. ROTATIONAL VELOCITIES FOR M DWARFS

    International Nuclear Information System (INIS)

    Jenkins, J. S.; Ramsey, L. W.; Jones, H. R. A.; Pavlenko, Y.; Barnes, J. R.; Pinfield, D. J.; Gallardo, J.

    2009-01-01

    We present spectroscopic rotation velocities (v sin i) for 56 M dwarf stars using high-resolution Hobby-Eberly Telescope High Resolution Spectrograph red spectroscopy. In addition, we have also determined photometric effective temperatures, masses, and metallicities ([Fe/H]) for some stars observed here and in the literature where we could acquire accurate parallax measurements and relevant photometry. We have increased the number of known v sin i values for mid M stars by around 80% and can confirm a weakly increasing rotation velocity with decreasing effective temperature. Our sample of v sin is peak at low velocities (∼3 km s -1 ). We find a change in the rotational velocity distribution between early M and late M stars, which is likely due to the changing field topology between partially and fully convective stars. There is also a possible further change in the rotational distribution toward the late M dwarfs where dust begins to play a role in the stellar atmospheres. We also link v sin i to age and show how it can be used to provide mid-M star age limits. When all literature velocities for M dwarfs are added to our sample, there are 198 with v sin i ≤ 10 km s -1 and 124 in the mid-to-late M star regime (M3.0-M9.5) where measuring precision optical radial velocities is difficult. In addition, we also search the spectra for any significant Hα emission or absorption. Forty three percent were found to exhibit such emission and could represent young, active objects with high levels of radial-velocity noise. We acquired two epochs of spectra for the star GJ1253 spread by almost one month and the Hα profile changed from showing no clear signs of emission, to exhibiting a clear emission peak. Four stars in our sample appear to be low-mass binaries (GJ1080, GJ3129, Gl802, and LHS3080), with both GJ3129 and Gl802 exhibiting double Hα emission features. The tables presented here will aid any future M star planet search target selection to extract stars with low v

  19. Genetic characterization of angular leaf spot resistance in selected ...

    African Journals Online (AJOL)

    Mr Tryphone

    2015-10-28

    Oct 28, 2015 ... Angular leaf spot disease (ALS) caused by Pseudocercospora griseola is one of the most important bean diseases in Tanzania. The bean landraces Beti-10, Nanka, Nanavala and Nkanamna used in this study have been identified as resistant to ALS but the nature of inheritance and mechanisms of.

  20. Incorporation of resistance to angular leaf spot and bean common ...

    African Journals Online (AJOL)

    Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola and Bean common mosaic and necrosis virus (BCMV/BCMNV) are important diseases of common bean in Tanzania that can cause severe yield reduction when uncontrolled. This study was conducted to incorporate resistant genes for ALS and ...

  1. Incorporation of resistance to angular leaf spot and bean common ...

    African Journals Online (AJOL)

    Luseko

    2013-07-03

    Jul 3, 2013 ... Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola and Bean common mosaic and necrosis virus (BCMV/BCMNV) are important diseases of common bean in Tanzania that can cause severe yield reduction when uncontrolled. This study was conducted to incorporate resistant genes ...

  2. Angular dispersion of protons transmitted through thin gold films

    International Nuclear Information System (INIS)

    Archubi, C.; Eckardt, J.C.; Lantschner, G.H.; Lovey, F.; Arista, N.R.; Denton, C.; Parra, C.; Valdes, J.; Zappa, F.

    2004-01-01

    The angular distributions of protons travelling through thin polycrystalline gold targets (∝15 nm) with incident energies in the range of 4-10 keV have been measured. The results confirm previous experiments at higher energies showing deviations from theoretical predictions based on the standard multiple scattering theory. In order to prove that the effect of crystal structure is one of the main causes of these deviations we have performed numerical simulations. To simulate the polycrystalline structure in a realistic way, we have made an analysis of the target by means of transmission electron microscopy (TEM) techniques. Including these characteristics in the simulation, together with the effect of vibrations and crystal disorder we analyzed the corresponding angular distribution. To evaluate the role of channeling, we also measured angular distributions of protons in a left angle 100 right angle gold foil and made the corresponding numerical simulations. The results show the critical influence of the target structure in the angular spectra of transmitted ions. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Numerical simulation of side heating for controlling angular ...

    Indian Academy of Sciences (India)

    However, it induces various types of distortions like angular, transverse, longitudinal, etc. Distor- tions induced ... strains and residual stress owing to the mismatch of thermal expansions in the weld and sur- rounding ... approaches, on the other hand, aim to minimize the residual stress during the welding process for given ...

  4. The phenomenon of nucleon emission at high angular momentum ...

    Indian Academy of Sciences (India)

    Since the drop in the separation energy is closely associated with the structural changes in the rotating nuclei, relative increase in neutron emission probability around certain values of angular momentum may be construed as evidence for the shape transition. A similar effect is predicted for 168Yb around ≈ 55ħ. We also ...

  5. Strong eld ionization of naphthalene: angular shifts and molecular potential

    DEFF Research Database (Denmark)

    Dimitrovski, Darko; Maurer, Jochen; Christensen, Lauge

    We analyze the photoelectron momentum distributions from strong eld ionization of xed-in-space naphthalene molecules by circularly polarized laser pulses. By direct comparison between experiment and theory, we show that the angular shifts in the photoelectron momentum distributions are very...

  6. Classical Angular Momentum of Light: A Paradox and its Resolution

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 10. Classical Angular Momentum of Light: A Paradox and its Resolution. K Vijay Kumar N Kumar. Classroom Volume 8 Issue 10 October 2003 pp 69-75. Fulltext. Click here to view fulltext PDF. Permanent link:

  7. Correlated angular distributions in τ+τ- semileptonic decays

    International Nuclear Information System (INIS)

    Dova, M.T.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Lacentre, P.E.

    1995-01-01

    The spin correlated angular distribution for τ - τ + pairs at energies of the Z 0 resonance, both decaying semi-leptonically up to 3 hadrons in each final state, was derived assuming general vector and axial vector couplings. The use of these distributions to test the V - A structure of the τ-W-ν τ vertex at LEP energies is analized. (orig.)

  8. Numerical simulation of side heating for controlling angular ...

    Indian Academy of Sciences (India)

    In the present study, a 3-D coupled transient thermal analysis model with auxiliary side heating (parallel heating) is developed to control angular distortion. During analysis, parallel heating flames are placed at several locations from weld line in cross direction. A user defined subroutine is used to apply transient heat source ...

  9. Equal channel angular pressing of pure aluminium—an analysis

    Indian Academy of Sciences (India)

    Equal channel angular pressing (ECAP) is a novel technique for producing ultra fine grain structures in submicron level by introducing a large amount of shear strain into the materials without changing the billet shape or dimensions. This process is well suited for aluminium alloys and is capable of producing ultra fine grain ...

  10. Variation in aggressiveness of Phaeoisariopsis griseola and angular ...

    African Journals Online (AJOL)

    Aggressiveness of fifteen isolates of Phaeoisariopsis griseola and variations in angular leaf spot symptom development in common bean were studied. The isolates were selected based on their virulence and genetic differences and represented Andean, Afro-Andean and Mesoamerican groups of P. griseola.

  11. Angular distribution of photoelectrons from atomic oxygen, nitrogen, and carbon

    Science.gov (United States)

    Manson, S. T.; Kennedy, D. J.; Starace, A. F.; Dill, D.

    1974-01-01

    The angular distribution of photoelectrons from atomic oxygen is investigated using Hartree-Fock (HF) wave functions. The correct formulation is used to compare HS and HF results. Agreement between these results is good and the HS calculations have been extended to atomic nitrogen and carbon as well.

  12. Angular anisotropy of the cosmic microwave background radiation

    International Nuclear Information System (INIS)

    Silk, J.

    1982-01-01

    The theory of fluctuations in the cosmic microwave background radiation is reviewed. Anisotropy on large-scale (dipole and quadrupole) and on small scales is discussed. The smoothing effects of secondary ionization (fractional ionization x) are found to be unimportant over an angular scale greater than approx.= 5(OMEGAx)sup(1/3) degrees. (author)

  13. Holographic toolkit for optical communication beyond orbital angular momentum

    CSIR Research Space (South Africa)

    Rosales-Guzman, C

    2016-09-01

    Full Text Available , suggested over 30 years ago, comprises the use of spatial modes of light as information carriers. Along this direction, light beams endowed with orbital angular momentum (OAM) have been demonstrated as potential information carriers in both, free space...

  14. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

    Science.gov (United States)

    Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dünner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-Yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.

    2016-08-01

    The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe ˜ 70 % of the sky. A variable-delay polarization modulator provides modulation of the polarization at ˜ 10 Hz to suppress the 1/ f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.

  15. Search for new physics in dijet mass and angular distributions

    Indian Academy of Sciences (India)

    We present a search for physics beyond the Standard Model in proton–proton collisions at a centre-of-mass energy of s = 7 TeV, performed with the ATLAS detector at the Large Hadron Collider (LHC). No evidence for new physics is found in dijet mass and angular distributions and stringent limits are set on a variety of ...

  16. Angular distributions and total yield of laser ablated silver

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Nordskov, A.; Schou, Jørgen

    1997-01-01

    The angular distribution of laser ablated silver has been measured in situ with a newly constructed setup with an array of microbalances. The distribution is strongly peaked in the forward direction corresponding to cospθ, where p varies between 5 and 9 for laser fluences from 2 to 7 J/cm2 at 355...

  17. Generation of ultraviolet radiation with wide angular tolerance in ...

    Indian Academy of Sciences (India)

    Tangential phase-matching has been realised in cesium lithium borate (CLBO) crystal for the first time for the generation of fourth harmonic (266 nm) of Nd:YAG and third harmonic (226.7 nm) of a dye laser radiation by second harmonic generation and sum-frequency mixing with the angular tolerance as large as 22 mrad ...

  18. Quantitatively measuring the orbital angular momentum density of light : Presentation

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2013-08-01

    Full Text Available Although many techniques are efficient at measuring optical orbital angular momentum (OAM), they do not allow one to obtain a quantitative measurement for the OAM density across an optical field and instead only measure its global OAM. Numerous...

  19. Exact angular momentum projection based on cranked HFB solution

    Energy Technology Data Exchange (ETDEWEB)

    Enami, Kenichi; Tanabe, Kosai; Yosinaga, Naotaka [Saitama Univ., Urawa (Japan). Dept. of Physics

    1998-03-01

    Exact angular momentum projection of cranked HFB solutions is carried out. It is reconfirmed from this calculation that cranked HFB solutions reproduce the intrinsic structure of deformed nucleus. The result also indicates that the energy correction from projection is important for further investigation of nuclear structure. (author)

  20. Angular momentum projection of tilted axis rotating states

    Energy Technology Data Exchange (ETDEWEB)

    Oi, M.; Onishi, N.; Tajima, N. [Tokyo Univ. (Japan); Horibata, T.

    1998-03-01

    We applied an exact angular momentum projection to three dimensional cranked HFB (3d-CHFB) states. Tilted axis rotating states (TAR) and principal axis rotating states (PAR) are compared. It is shown that TAR is more adequate than PAR for description of the back bending phenomena driven by tilted rotation or wobbling motion. (author)

  1. Generation of ultraviolet radiation with wide angular tolerance in ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 55; Issue 3 ... Non-linear optics; ultraviolet radiation; tangential phase-matching; Sellmeier dispersion ... of Nd:YAG and third harmonic (226.7 nm) of a dye laser radiation by second harmonic generation and sum-frequency mixing with the angular tolerance as large as ...

  2. The vorticity and angular momentum budgets of Asian summer ...

    Indian Academy of Sciences (India)

    The study delineates the vorticity and angular momentum balances of Asian summer monsoon during the evolution and established phases. It also elucidates the differences between these balances in the National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalysis ...

  3. Angular dose dependence of Matrixx TM and its calibration.

    Science.gov (United States)

    Wolfsberger, Luciant D; Wagar, Matthew; Nitsch, Paige; Bhagwat, Mandar S; Zygmanski, Piotr

    2010-01-28

    One of the applications of MatriXX (IBA Dosimetry) is experimental verification of dose for IMRT, VMAT, and tomotherapy. For cumulative plan verification, dose is delivered for all the treatment gantry angles to a stationary detector. Experimental calibration of MatriXX detector recommended by the manufacturer involves only AP calibration fields and does not address angular dependency of MatriXX. Angular dependency may introduce dose bias in cumulative plan verification if not corrected. For this reason, we characterized angular dependency of MatriXX and developed a method for its calibration. We found relatively large discrepancies in responses to posterior vs. anterior fields for four MatriXX (Evolution series) detectors (up to 11%), and relatively large variability of responses as a function of gantry angle in the gantry angle ranges of 91 degrees-110 degrees and 269 degrees-260 degrees. With our calibration method, the bias due to angular dependency is effectively removed in experimental verification of IMRT and VMAT plans.

  4. The angular ordering in soft-gluon emission

    International Nuclear Information System (INIS)

    Tesima, K.

    1987-01-01

    The way to evaluate multi-parton cross-sections systematically is discussed. In the leading-double-log approximation in QCD, the successive emission of soft gluons is at successively smaller angles. The angular ordering, however, is violated in the next-to-leading order

  5. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

    Science.gov (United States)

    Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dunner, R.; Essinger-Hileman, T.; Eimer, J.; hide

    2015-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe approx.70% of the sky. A variable-delay polarization modulator provides modulation of the polarization at approx.10Hz to suppress the 1/f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.

  6. Synchronization of colloidal rotors through angular optical binding

    Czech Academy of Sciences Publication Activity Database

    Simpson, Stephen Hugh; Chvátal, Lukáš; Zemánek, Pavel

    2016-01-01

    Roč. 93, č. 2 (2016), 023842:1-12 ISSN 2469-9926 R&D Projects: GA ČR GB14-36681G Institutional support: RVO:68081731 Keywords : hydrodynamic properties * colloidal rotors * angular optical binding Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.925, year: 2016

  7. Data visualization with D3 and AngularJS

    CERN Document Server

    Körner, Christoph

    2015-01-01

    If you are a web developer with experience in AngularJS and want to implement interactive visualizations using D3.js, this book is for you. Knowledge of SVG or D3.js will give you an edge to get the most out of this book.

  8. A new uncertainty relation for angular momentum and angle

    International Nuclear Information System (INIS)

    Kranold, H.U.

    1984-01-01

    An uncertainty relation of the form ΔL 2 ΔSo >=sup(h/2π)/sub(2) is derived for angular momentum and angle. The non-linear operator So measures angles and has a simple interpretation. Subject to very general conditions of rotational invariance the above relation is unique. Radial momentum is not quantized

  9. Fission fragment mass and angular distributions: Probes to study ...

    Indian Academy of Sciences (India)

    cesses (often commonly called quasifission in the literature) differ subtly in terms of the observables which are measured in a reaction, and disentangling the contributions of each of these processes is very challenging. While FF is observed when the fission barrier becomes vanishingly small at very high angular momenta, ...

  10. Earth Rotation and Coupling to Changes in Atmospheric Angular Momentum

    Science.gov (United States)

    Rosen, Richard D.; Frey, H. (Technical Monitor)

    2000-01-01

    The research supported under the contract dealt primarily with: (a) the mechanisms responsible for the exchange of angular momentum between the solid Earth and atmosphere; (b) the quality of the data sets used to estimate atmospheric angular momentum; and (c) the ability of these data and of global climate models to detect low-frequency signals in the momentum and, hence, circulation of the atmosphere. Three scientific papers reporting on the results of this research were produced during the course of the contract. These papers identified the particular torques responsible for the peak in atmospheric angular momentum and length-of-day during the 1982-93 El Nino event, and, more generally, the relative roles of torques over land and ocean in explaining the broad spectrum of variability in the length-of-day. In addition, a tendency for interannual variability in atmospheric angular momentum to increase during the last several decades of the 20th century was found in both observations and a global climate model experiment.

  11. Data compilation of angular distributions of sputtered atoms

    International Nuclear Information System (INIS)

    Yamamura, Yasunori; Takiguchi, Takashi; Tawara, Hiro.

    1990-01-01

    Sputtering on a surface is generally caused by the collision cascade developed near the surface. The process is in principle the same as that causing radiation damage in the bulk of solids. Sputtering has long been regarded as an undesirable dirty effect which destroys the cathodes and grids in gas discharge tubes or ion sources and contaminates plasma and the surrounding walls. However, sputtering is used today for many applications such as sputter ion sources, mass spectrometers and the deposition of thin films. Plasma contamination and the surface erosion of first walls due to sputtering are still the major problems in fusion research. The angular distribution of the particles sputtered from solid surfaces can possibly provide the detailed information on the collision cascade in the interior of targets. This report presents a compilation of the angular distribution of sputtered atoms at normal incidence and oblique incidence in the various combinations of incident ions and target atoms. The angular distribution of sputtered atoms from monatomic solids at normal incidence and oblique incidence, and the compilation of the data on the angular distribution of sputtered atoms are reported. (K.I.)

  12. Generation of ultraviolet radiation with wide angular tolerance in ...

    Indian Academy of Sciences (India)

    CLBO) crystal for the first time for the generation of fourth harmonic (266 nm) of Nd:YAG and third harmonic. (226.7 nm) of a dye laser radiation by second harmonic generation and sum-frequency mixing with the angular tolerance as large as ...

  13. Angular dependence of IPEN parallels plates ionization chambers

    International Nuclear Information System (INIS)

    Albuquerque, M. da P.; Caldas, L.V.E.

    1989-01-01

    The angular dependence of parallel plates ionization chambers for X-radiation of low energy is studied, aiming at the correction of any influence that may occur, due to positioning. The national fabrication chambers behaviour is evaluated and the results are compared with imported similar chambers. (C.G.C.) [pt

  14. Angular dependence of EEDF in ion-beam plasma

    International Nuclear Information System (INIS)

    Dudin, S.V.

    1995-01-01

    In a previous paper the results of measurements of electron energy distribution function (EEDF) in ion-beam plasma created by low energy broad ion beam had been presented regardless of the angular dependence of the electron distribution. The present work is specifically aimed towards elucidating the spatial structure of the EEDF in the ion-beam plasma. To solve this problem combination of the techniques of cylindrical probe, large plate probe (5 x 5 mm) and two-grid enegoanalyzer was used. Directional operation of the probes makes possible measurement of angular dependence of electron distribution function which is anisotropic in high energy region. To optimize the construction of the probe-analyzer, experiments with grids were performed, which had different size, mesh, and transparency, under different potentials, and with different distances between grids. Numerical simulation of the analyzer was performed too. It is derived that optimal design for measurements in isotropic plasma is the most plate, thin two-grid probe with maximum angular covering. Investigation of angular dependence of EEDF has shown that the distribution of trapped electrons is completely isotropic, whereas in the energy range of var-epsilon > e var-phi pl (var-phi pl - plasma potential) a strong anisotropy of the EEDF is observed

  15. QCD in the infrared with exact angular integrations

    NARCIS (Netherlands)

    Atkinson, D; Bloch, J.C R

    1998-01-01

    In a previous paper we have shown that in quantum chromodynamics the gluon propagator vanishes in the infrared limit, while the ghost propagator is more singular than a simple pole. These results were obtained after angular averaging, but here we go beyond this approximation and perform an exact

  16. Angular distribution of cosmic muons using INO–ICAL prototype ...

    Indian Academy of Sciences (India)

    2012-11-10

    Nov 10, 2012 ... Here, 2, 4, 7 and 9 layers are used in trigger criteria. This particular choice helps to increase the detector solid angular acceptance. 3. Event data analysis. Event data consist of two informations: (i) cosmic ray muon hits per layer and (ii) the corresponding time of arrival. Here, hit information is only used to ...

  17. The phenomenon of nucleon emission at high angular momentum ...

    Indian Academy of Sciences (India)

    This is contrary to the classical notion of monotonously decreasing separation energy with increasing angular momentum. We have reported in ref. [1] some results for 156Er formed in the reaction 96Zr (64Ni,xn) 155Er, which are in good agreement with the experimental results of Henss et al [2] for single neutron emission.

  18. Angular Momentum across the Hubble sequence from the CALIFA survey

    NARCIS (Netherlands)

    Falcón-Barroso, Jesús; Lyubenova, Mariya; van de Ven, Glenn

    We investigate the stellar angular momentum of galaxies across the Hubble sequence from the CALIFA survey. The distribution of CALIFA elliptical and lenticular galaxies in the λRe - ɛe diagram is consistent with that shown by the Atlas3D survey. Our data, however, show that the location of spiral

  19. Numerical simulation of side heating for controlling angular ...

    Indian Academy of Sciences (India)

    One side multipass 'V' butt weld configuration is used for this study. A series of observational tests are done with a special experimental fixture using Manual Metal Arc Welding (MMAW) to validate the proposed FEA model. It is found that the angular distortion has decreased from 2 mm to 0.4 mm with change in side heating ...

  20. A perturbed angular correlation spectrometer for material science ...

    Indian Academy of Sciences (India)

    Abstract. A four-detector perturbed angular correlation (PAC) spectrometer has been developed with ultra-fast BaF2 detectors to acquire four coincidence spectra simultane- ously, two at 180° and two at 90°. This spectrometer has double efficiency compared to that of a three-detector set-up. Higher efficiency is desirable for ...

  1. The phenomenon of nucleon emission at high angular momentum ...

    Indian Academy of Sciences (India)

    physics pp. 75–93. The phenomenon of nucleon emission at high angular momentum states of fused compound systems. T R RAJASEKARAN1 £, S SELVARAJ2 and S SANTHOSH KUMAR3. 1Department of Physics, Manonmaniam Sundaranar University, Tirunelveli 627 012, India. 2Department of Physics, The M.D.T. ...

  2. THE SIMULATION OF SCATTERING OF ELECTROMAGNETIC WAVES ON ANGULAR STRUCTURES.

    Directory of Open Access Journals (Sweden)

    P. A. Preobrazhensky

    2017-02-01

    Full Text Available The paper discusses the characteristics of scattering of electromagnetic waves on the angular diffraction structures. The solution of the problem is based on the method of integral equations. A comparative analysis of the scattering characteristics of structures with different shape is carried out.

  3. A perturbed angular correlation spectrometer for material science ...

    Indian Academy of Sciences (India)

    A four-detector perturbed angular correlation (PAC) spectrometer has been developed with ultra-fast BaF2 detectors to acquire four coincidence spectra simultaneously, two at 180° and two at 90°. This spectrometer has double efficiency compared to that of a three-detector set-up. Higher efficiency is desirable for PAC ...

  4. Continuous Variable Entanglement and Squeezing of Orbital Angular Momentum States

    DEFF Research Database (Denmark)

    Lassen, Mikael Østergaard; Leuchs, Gerd; Andersen, Ulrik Lund

    2009-01-01

    We report the first experimental characterization of the first-order continuous variable orbital angular momentum states. Using a spatially nondegenerate optical parametric oscillator (OPO) we produce quadrature entanglement between the two first-order Laguerre-Gauss modes. The family of orbital...

  5. Energy and angular distributions of backscattered electrons from ...

    Indian Academy of Sciences (India)

    Abstract. The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between EB = 50 eV and 5000. eV. The angle of incidence α and take-off angle θ are ...

  6. Energy and angular distributions of backscattered electrons from ...

    Indian Academy of Sciences (India)

    The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between B = 50 eV and 5000 eV. The angle of incidence α and take-off angle are chosen to have ...

  7. Implementing quantum walks using orbital angular momentum of classical light

    CSIR Research Space (South Africa)

    Goyal, SK

    2013-06-01

    Full Text Available We present an implementation scheme for a quantum walk in the orbital angular momentum space of a laser beam. The scheme makes use of a ring interferometer, containing a quarter-wave plate and a q plate. This setup enables one to perform...

  8. Equal Channel Angular Extrusion Simulation of High-Nb Containing β-γ TiAl Alloys

    Directory of Open Access Journals (Sweden)

    Lai-qi Zhang

    2015-01-01

    Full Text Available TiAl alloys containing high Nb are significantly promising for high-temperature structural applications in aerospace and automotive industries. Unfortunately the low plasticity at room temperature limits their extensive applications. To improve the plasticity, not only optimizing the opposition, but also refining grain size through equal channel angular extrusion (ECAE is necessary. The equal channel angular extrusion simulation of Ti-44Al-8Nb-(Cr,Mn,B,Y(at% alloy was investigated by using the Deform-3D software. The influences of friction coefficient, extrusion velocity, and different channel angles on effective strain, damage factor, and the load on the die were analyzed. The results indicate that, with the increasing of friction coefficient, effective strain is enhanced. The extrusion velocity has little effect on the uniformity of effective strain; in contrast it has large influence on the damage factor. Thus smaller extrusion rate is more appropriate. Under the condition of different channel angles, the larger one results in the lower effective strain magnitude and better strain distribution uniformity.

  9. Power calculation of linear and angular incremental encoders

    Science.gov (United States)

    Prokofev, Aleksandr V.; Timofeev, Aleksandr N.; Mednikov, Sergey V.; Sycheva, Elena A.

    2016-04-01

    Automation technology is constantly expanding its role in improving the efficiency of manufacturing and testing processes in all branches of industry. More than ever before, the mechanical movements of linear slides, rotary tables, robot arms, actuators, etc. are numerically controlled. Linear and angular incremental photoelectric encoders measure mechanical motion and transmit the measured values back to the control unit. The capabilities of these systems are undergoing continual development in terms of their resolution, accuracy and reliability, their measuring ranges, and maximum speeds. This article discusses the method of power calculation of linear and angular incremental photoelectric encoders, to find the optimum parameters for its components, such as light emitters, photo-detectors, linear and angular scales, optical components etc. It analyzes methods and devices that permit high resolutions in the order of 0.001 mm or 0.001°, as well as large measuring lengths of over 100 mm. In linear and angular incremental photoelectric encoders optical beam is usually formulated by a condenser lens passes through the measuring unit changes its value depending on the movement of a scanning head or measuring raster. Past light beam is converting into an electrical signal by the photo-detecter's block for processing in the electrical block. Therefore, for calculating the energy source is a value of the desired value of the optical signal at the input of the photo-detecter's block, which reliably recorded and processed in the electronic unit of linear and angular incremental optoelectronic encoders. Automation technology is constantly expanding its role in improving the efficiency of manufacturing and testing processes in all branches of industry. More than ever before, the mechanical movements of linear slides, rotary tables, robot arms, actuators, etc. are numerically controlled. Linear and angular incremental photoelectric encoders measure mechanical motion and

  10. Continuous theta burst stimulation of angular gyrus reduces subjective recollection.

    Directory of Open Access Journals (Sweden)

    Yasemin Yazar

    Full Text Available The contribution of lateral parietal regions such as the angular gyrus to human episodic memory has been the subject of much debate following widespread observations of left parietal activity in healthy volunteers during functional neuroimaging studies of memory retrieval. Patients with lateral parietal lesions are not amnesic, but recent evidence indicates that their memory abilities may not be entirely preserved. Whereas recollection appears intact when objective measures such as source accuracy are used, patients often exhibit reduced subjective confidence in their accurate recollections. When asked to recall autobiographical memories, they may produce spontaneous narratives that lack richness and specificity, but can remember specific details when prompted. Two distinct theoretical accounts have been proposed to explain these results: that the patients have a deficit in the bottom-up capturing of attention by retrieval output, or that they have an impairment in the subjective experience of recollection. The present study aimed to differentiate between these accounts using continuous theta burst stimulation (cTBS in healthy participants to disrupt function of specific left parietal subregions, including angular gyrus. Inconsistent with predictions of the attentional theory, angular gyrus cTBS did not result in greater impairment of free recall than cued recall. Supporting predictions of the subjective recollection account, temporary disruption of angular gyrus was associated with highly accurate source recollection accuracy but a selective reduction in participants' rated source confidence. The findings are consistent with a role for angular gyrus in the integration of memory features into a conscious representation that enables the subjective experience of remembering.

  11. Effect of the energy spectrum and angular momentum of pre-scission neutrons on the prediction of fission fragment angular anisotropy by the models

    Science.gov (United States)

    Soheyli, Saeed; Khanlari, Marzieh Varasteh

    2016-04-01

    Effects of the various neutron emission energy spectra, as well as the influence of the angular momentum of pre-scission neutrons on theoretical predictions of fission fragment angular anisotropies for several heavy-ion induced fission systems are considered. Although theoretical calculations of angular anisotropy are very sensitive to neutron emission correction, the effects of the different values of kinetic energy of emitted neutrons derived from the various neutron emission energy spectra before reaching to the saddle point on the prediction of fission fragment angular distribution by the model are not significant and can be neglected, since these effects on angular anisotropies of fission fragments for a wide range of fissility parameters and excitation energies of compound nuclei are not more than 10%. Furthermore, the theoretical prediction of fission fragment angular anisotropy is not sensitive to the angular momentum of emitted neutrons.

  12. Effect of old age on human skeletal muscle force-velocity and fatigue properties

    Science.gov (United States)

    Callahan, Damien M.

    2011-01-01

    It is generally accepted that the muscles of aged individuals contract with less force, have slower relaxation rates, and demonstrate a downward shift in their force-velocity relationship. The factors mediating age-related differences in skeletal muscle fatigue are less clear. The present study was designed to test the hypothesis that age-related shifts in the force-velocity relationship impact the fatigue response in a velocity-dependent manner. Three fatigue protocols, consisting of intermittent, maximum voluntary knee extension contractions performed for 4 min, were performed by 11 young (23.5 ± 0.9 yr, mean ± SE) and 10 older (68.9 ± 4.3) women. The older group fatigued less during isometric contractions than the young group (to 71.1 ± 3.7% initial torque and 59.8 ± 2.5%, respectively; P = 0.02), while the opposite was true during contractions performed at a relatively high angular velocity of 270°·s−1 (old: 28.0 ± 3.9% initial power, young: 52.1 ± 6.9%; P Fatigue was not different (P = 0.74) between groups during contractions at an intermediate velocity, which was selected for each participant based on their force-velocity relationship. There was a significant association between force-velocity properties and fatigue induced by the intermediate-velocity fatigue protocol in the older (r = 0.72; P = 0.02) and young (r = 0.63; P = 0.04) groups. These results indicate that contractile velocity has a profound impact on age-related skeletal muscle fatigue resistance and suggest that changes in the force-velocity relationship partially mediate this effect. PMID:21868683

  13. A transverse oscillation approach for estimation of three-dimensional velocity vectors, part II: experimental validation.

    Science.gov (United States)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2014-10-01

    The 3-D transverse oscillation method is investigated by estimating 3-D velocities in an experimental flow-rig system. Measurements of the synthesized transverse oscillating fields are presented as well. The method employs a 2-D transducer; decouples the velocity estimation; and estimates the axial, transverse, and elevation velocity components simultaneously. Data are acquired using a research ultrasound scanner. The velocity measurements are conducted with steady flow in sixteen different directions. For a specific flow direction with [α, ß] = [45, 15]°, the mean estimated velocity vector at the center of the vessel is (v(x), v(y), v(z)) = (33.8, 34.5, 15.2) ± (4.6, 5.0, 0.6) cm/s where the expected velocity is (34.2, 34.2, 13.0) cm/s. The velocity magnitude is 50.6 ± 5.2 cm/s with a bias of 0.7 cm/s. The flow angles α and ß are estimated as 45.6 ± 4.9° and 17.6 ± 1.0°. Subsequently, the precision and accuracy are calculated over the entire velocity profiles. On average for all direction, the relative mean bias of the velocity magnitude is -0.08%. For α and ß, the mean bias is -0.2° and -1.5°. The relative standard deviations of the velocity magnitude ranges from 8 to 16%. For the flow angles, the ranges of the mean angular deviations are 5° to 16° and 0.7° and 8°.

  14. Three-dimensional simulation of the motion of a single particle under a simulated turbulent velocity field

    Science.gov (United States)

    Moreno-Casas, P. A.; Bombardelli, F. A.

    2015-12-01

    A 3D Lagrangian particle tracking model is coupled to a 3D channel velocity field to simulate the saltation motion of a single sediment particle moving in saltation mode. The turbulent field is a high-resolution three dimensional velocity field that reproduces a by-pass transition to turbulence on a flat plate due to free-stream turbulence passing above de plate. In order to reduce computational costs, a decoupled approached is used, i.e., the turbulent flow is simulated independently from the tracking model, and then used to feed the 3D Lagrangian particle model. The simulations are carried using the point-particle approach. The particle tracking model contains three sub-models, namely, particle free-flight, a post-collision velocity and bed representation sub-models. The free-flight sub-model considers the action of the following forces: submerged weight, non-linear drag, lift, virtual mass, Magnus and Basset forces. The model also includes the effect of particle angular velocity. The post-collision velocities are obtained by applying conservation of angular and linear momentum. The complete model was validated with experimental results from literature within the sand range. Results for particle velocity time series and distribution of particle turbulent intensities are presented.

  15. Variable Mixed Orbital Character in the Photoelectron Angular Distribution of NO_{2}

    Science.gov (United States)

    Laws, Benjamin A.; Cavanagh, Steven J.; Lewis, Brenton R.; Gibson, Stephen T.

    2017-06-01

    NO_{2} a key component of photochemical smog and an important species in the Earth's atmosphere, is an example of a molecule which exhibits significant mixed orbital character in the HOMO. In photoelectron experiments the geometric properties of the parent anion orbital are reflected in the photoelectron angular distribution (PAD), an area of research that has benefited largely from the ability of velocity-map imaging (VMI) to simultaneously record both the energetic and angular information, with 100% collection efficiency. Photoelectron spectra of NO_{2}^{-}, taken over a range of wavelengths (355nm-520nm) with the ANU's VMI spectrometer, reveal an anomalous jump in the anisotropy parameter near threshold. Consequently, the orbital behavior of NO_{2}^{-} appears to be quite different near threshold compared to detachment at higher photon energies. This surprising effect is due to the Wigner Threshold law, which causes p orbital character to dominate the photodetachment cross-section near threshold, before the mixed s/d orbital character becomes significant at higher electron kinetic energies. By extending recent work on binary character models to form a more general expression, the variable mixed orbital character of NO_{2}^{-} is able to be described. This study provides the first multi-wavelength NO_{2} anisotropy data, which is shown to be in decent agreement with much earlier zero-core model predictions of the anisotropy parameter. K. J. Reed, A. H. Zimmerman, H. C. Andersen, and J. I. Brauman, J. Chem. Phys. 64, 1368, (1976). doi:10.1063/1.432404 D. Khuseynov, C. C. Blackstone, L. M. Culberson, and A. Sanov, J. Chem. Phys. 141, 124312, (2014). doi:10.1063/1.4896241 W. B. Clodius, R. M. Stehman, and S. B. Woo, Phys. Rev. A. 28, 760, (1983). doi:10.1103/PhysRevA.28.760 Research supported by the Australian Research Council Discovery Project Grant DP160102585

  16. A New Shape Description Method Using Angular Radial Transform

    Science.gov (United States)

    Lee, Jong-Min; Kim, Whoi-Yul

    Shape is one of the primary low-level image features in content-based image retrieval. In this paper we propose a new shape description method that consists of a rotationally invariant angular radial transform descriptor (IARTD). The IARTD is a feature vector that combines the magnitude and aligned phases of the angular radial transform (ART) coefficients. A phase correction scheme is employed to produce the aligned phase so that the IARTD is invariant to rotation. The distance between two IARTDs is defined by combining differences in the magnitudes and aligned phases. In an experiment using the MPEG-7 shape dataset, the proposed method outperforms existing methods; the average BEP of the proposed method is 57.69%, while the average BEPs of the invariant Zernike moments descriptor and the traditional ART are 41.64% and 36.51%, respectively.

  17. Characteristic angular scales in cosmic microwave background radiation

    International Nuclear Information System (INIS)

    Ghasemi, F.; Bahraminasab, A.; Movahed, M.S.; Rahvar, S.; Sreenivasan, K.R.; Tabar, M.R.R.

    2006-12-01

    We investigate the stochasticity in temperature fluctuations in the cosmic microwave background (CMB) radiation data from the Wilkinson Microwave Anisotropy Probe. We show that the angular fluctuation of the temperature is a Markov process with a Markov angular scale, Markov 1.01 -0.07 +0.09 . We characterize the complexity of the CMB fluctuations by means of a Fokker-Planck or Langevin equation and measure the associated Kramers-Moyal coefficients for the fluctuating temperature field T(n-circumflex) and its increment, ΔT = T(n-circumflex 1 ) - T(n-circumflex 2 ). Through this method we show that temperature fluctuations in the CMB have fat tails compared to a Gaussian distribution. (author)

  18. Resilience of hybrid optical angular momentum qubits to turbulence

    Science.gov (United States)

    Farías, Osvaldo Jiménez; D'Ambrosio, Vincenzo; Taballione, Caterina; Bisesto, Fabrizio; Slussarenko, Sergei; Aolita, Leandro; Marrucci, Lorenzo; Walborn, Stephen P.; Sciarrino, Fabio

    2015-02-01

    Recent schemes to encode quantum information into the total angular momentum of light, defining rotation-invariant hybrid qubits composed of the polarization and orbital angular momentum degrees of freedom, present interesting applications for quantum information technology. However, there remains the question as to how detrimental effects such as random spatial perturbations affect these encodings. Here, we demonstrate that alignment-free quantum communication through a turbulent channel based on hybrid qubits can be achieved with unit transmission fidelity. In our experiment, alignment-free qubits are produced with q-plates and sent through a homemade turbulence chamber. The decoding procedure, also realized with q-plates, relies on both degrees of freedom and renders an intrinsic error-filtering mechanism that maps errors into losses.

  19. Angular dependence of the exchange bias for the bistable state

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yuhao [College of Physics and Electronic Information, Shanxi Normal University, Linfen 041004 (China); Research College of materials science, Shanxi Normal University, Linfen 041004 (China); Xu, Xiaohong, E-mail: xuxh@dns.sxnu.edu.cn [Research College of materials science, Shanxi Normal University, Linfen 041004 (China); Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University, Linfen 041004 (China)

    2017-06-15

    The angular dependence of the exchange bias (ADEB) has been investigated in detail when the exchange-coupled ferromagnetic (FM)/antiferromagnetic (AFM) bilayer is in the bistable state. Complete and incomplete jump phenomena were found at the intrinsic easy and hard axes, when they pass through two special positions making the angular deviation of 58.2826° and 121.7174° from the easy axis of the uniaxial anisotropy, respectively. The combination of these different types of the jump phenomena at the intrinsic easy and hard axes yields five distinct types of the ADEB. The physical condition for each type of ADEB is established. Additionally, the extreme value problem of the exchange bias field and coercivity are also discussed, which is an important technological issue in the design of the magnetoresistive and spintronic devices. These results enable us to make a comprehensive understanding of the experimental ADEB curves.

  20. Angular diameters of Magellanic Cloud plantary nebulae. I. Speckle interferometry

    International Nuclear Information System (INIS)

    Wood, P.R.; Bessell, M.S.; Dopita, M.A.

    1986-01-01

    Speckle interferometric angular diameters of Magellanic Cloud planetary nebulae are presented. The mass of ionized gas in each nebula has been derived from the angular diameter and published H-beta line fluxes; the derives masses range from less than 0.006 to more than 0.19 solar mass. The planetary nebulae observed were the brightest in the Magellanic Clouds; consequently, they are all relatively small, young, bright, and dense. They are almost certainly only partially ionized, so that the masses derived for the ionized parts of the nebula are lower limits to the total nebula mass. The properties of the Magellanic Cloud nebulae are compared with those of planetary nebulae at the galactic center. 27 references

  1. Relativistic correction to the deuteron magnetic moment and angular condition

    International Nuclear Information System (INIS)

    Kondratyuk, L.A.; Strikman, M.I.

    1983-01-01

    The relativistic correction (RC) to the deuteron magnetic moment μsub(d) is investigated using the light-cone dynamics. The restrictions imposed by the angular condition on the electromagnetic current operator of deuteron are discussed in detail. It is shown that the additive model for the current operator of interacting consistuencies is consistent with the angular condition only for the two first terms of expansion of the ''good'' electromagnetic current component jsub(+) in powers of the momentum transfer q. The RC into μsub(d) is calculated using the mattix element of the ''good'' component. The account of RC decreases essentially the discrepancy between the theoretical and experimental values. The value of Δsub(μ) is determined for the Hamada-Johnston potential hard core potential (0.93x10 -2 ) for the Reid soft core potential (0.71x10 -2 ) and for the Paris potential (0.63x10 -2 )

  2. Investigating pointing tasks across angularly coupled display areas

    DEFF Research Database (Denmark)

    Hennecke, Fabian; De Luca, Alexander; Nguyen, Ngo Dieu Huong

    2013-01-01

    user performance still hold – in particular when pointing is performed across differently oriented areas. To answer this question, we conducted an experiment on an angularly coupled display – the Curve – with two input conditions: direct touch and indirect mouse pointer. Our findings show......Pointing tasks are a crucial part of today’s graphical user interfaces. They are well understood for flat displays and most prominently are modeled through Fitts’ Law. For novel displays (e.g., curved displays with multi-purpose areas), however, it remains unclear whether such models for predicting...... that the target position affects overall pointing speed and offset in both conditions. However, we also found that Fitts’ Law can in fact still be used to predict performance as on flat displays. Our results help designers to optimize user interfaces on angularly coupled displays when pointing tasks are involved....

  3. Angular dependence of the parallel plate ionization chambers of Ipen

    International Nuclear Information System (INIS)

    Albuquerque, M. da P.P.; Caldas, L.

    1989-08-01

    The ionization chambers with parallel plates designed and constructed at IPEN for the dosimetry of soft X-radiation fields were studied in relation to thein angular dependence between O and +- 90 0 . The objective of this study is to verify the chambers response variation for small positioning errors during the field dosimetry used in Radiotherapy. The results were compared with those of commercial parallel plate ionization chambers used as secondary and testiary standards. (author) [pt

  4. Spin and orbital angular momentum propagation in anisotropic media: theory

    International Nuclear Information System (INIS)

    Picón, Antonio; Benseny, Albert; Mompart, Jordi; Calvo, Gabriel F

    2011-01-01

    This paper is devoted to a study of the propagation of light beams carrying orbital angular momentum in optically anisotropic media. We first review some properties of homogeneous anisotropic media, and describe how the paraxial formalism is modified in order to proceed with a new approach dealing with the general setting of paraxial propagation along uniaxial inhomogeneous media. This approach is suitable for describing space-variant optical-axis phase plates

  5. Uniqueness for the inverse backscattering problem for angularly controlled potentials

    International Nuclear Information System (INIS)

    Rakesh; Uhlmann, Gunther

    2014-01-01

    We consider the problem of recovering a smooth, compactly supported potential on R 3 from its backscattering data. We show that if two such potentials have the same backscattering data and the difference of the two potentials has controlled angular derivatives, then the two potentials are identical. In particular, if two potentials differ by a finite linear combination of spherical harmonics with radial coefficients and have the same backscattering data then the two potentials are identical. (paper)

  6. Spatial Angular Compounding Technique for H-Scan Ultrasound Imaging.

    Science.gov (United States)

    Khairalseed, Mawia; Xiong, Fangyuan; Kim, Jung-Whan; Mattrey, Robert F; Parker, Kevin J; Hoyt, Kenneth

    2018-01-01

    H-Scan is a new ultrasound imaging technique that relies on matching a model of pulse-echo formation to the mathematics of a class of Gaussian-weighted Hermite polynomials. This technique may be beneficial in the measurement of relative scatterer sizes and in cancer therapy, particularly for early response to drug treatment. Because current H-scan techniques use focused ultrasound data acquisitions, spatial resolution degrades away from the focal region and inherently affects relative scatterer size estimation. Although the resolution of ultrasound plane wave imaging can be inferior to that of traditional focused ultrasound approaches, the former exhibits a homogeneous spatial resolution throughout the image plane. The purpose of this study was to implement H-scan using plane wave imaging and investigate the impact of spatial angular compounding on H-scan image quality. Parallel convolution filters using two different Gaussian-weighted Hermite polynomials that describe ultrasound scattering events are applied to the radiofrequency data. The H-scan processing is done on each radiofrequency image plane before averaging to get the angular compounded image. The relative strength from each convolution is color-coded to represent relative scatterer size. Given results from a series of phantom materials, H-scan imaging with spatial angular compounding more accurately reflects the true scatterer size caused by reductions in the system point spread function and improved signal-to-noise ratio. Preliminary in vivo H-scan imaging of tumor-bearing animals suggests this modality may be useful for monitoring early response to chemotherapeutic treatment. Overall, H-scan imaging using ultrasound plane waves and spatial angular compounding is a promising approach for visualizing the relative size and distribution of acoustic scattering sources. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

  7. Automatic spectrometer for γ-γ angular correlation

    International Nuclear Information System (INIS)

    Saxena, R.N.; Monteiro, M.T.S.; Bairrio Nuevo Junior, A.

    1974-01-01

    An automated γ-γ angular correlation spectrometer is described in detail. Eletronic arrangements used in integral and differential measurements have also been described. In part I there is a short theoretical introduction, the experimental arrangement is described in part II. The results of the directional correlation measurement of γ-cascades in 60 Ni and 75 As and of the lifetime measurement of excited states in 181 Ta and 81 Br have been described in part III

  8. Tunnelling of orbital angular momentum in parallel optical waveguides

    International Nuclear Information System (INIS)

    Alexeyev, C N; Fadeyeva, T A; Yavorsky, M A; Boklag, N A

    2011-01-01

    We study the evolution of circularly polarized optical vortices (OVs) in the system of two coupled few-mode optical fibres. We demonstrate that upon propagation OVs tunnel into the adjacent fibre as a complex superposition of OVs that comprise also OVs of opposite polarization and topological charge. The initial OV may tunnel into the other fibre as the same vortex state of lesser energy. The evolution of the orbital angular momentum in coupled fibres is studied

  9. prevalence of angular leaf spot disease and sources of resistance

    African Journals Online (AJOL)

    USER

    la gravité et l'incidence de la maladie et l'effet des pratiques agronomiques et des facteurs environnement aux sur la prévalence de ...... Thika Kenya. Saettler, A.W. 1991. Angular leaf spot. In: Compendium of bean diseases, 15-16. Hall, R. (Ed.). APS Press.St Paul, USA. Sahile, S., Ahmed, S., Fininsa, C., Abang, M. M. and ...

  10. Angular-momentum nonclassicality by breaking classical bounds on statistics

    International Nuclear Information System (INIS)

    Luis, Alfredo; Rivas, Angel

    2011-01-01

    We derive simple practical procedures revealing the quantum behavior of angular momentum variables by the violation of classical upper bounds on the statistics. Data analysis is minimum and definite conclusions are obtained without evaluation of moments, or any other more sophisticated procedures. These nonclassical tests are very general and independent of other typical quantum signatures of nonclassical behavior such as sub-Poissonian statistics, squeezing, or oscillatory statistics, being insensitive to the nonclassical behavior displayed by other variables.

  11. Potential model for fusion and angular momentum localisation

    International Nuclear Information System (INIS)

    Hugi, M.; Jarczyk, L.; Kamys, B.

    1981-01-01

    The elastic scattering and fusion cross sections for different heavy-ion systems with (A 1 + A 2 ) 9 Be, 8 Be) reaction as a representative example for direct processes in the system 9 Be + 28 Si is well reproduced by a DWBA calculation which in turn leads to a localisation of fusion and direct processes in mutually exclusive regions of the angular momentum space. (author)

  12. Unveiling the orbital angular momentum and acceleration of electron beams.

    Science.gov (United States)

    Shiloh, Roy; Tsur, Yuval; Remez, Roei; Lereah, Yossi; Malomed, Boris A; Shvedov, Vladlen; Hnatovsky, Cyril; Krolikowski, Wieslaw; Arie, Ady

    2015-03-06

    New forms of electron beams have been intensively investigated recently, including vortex beams carrying orbital angular momentum, as well as Airy beams propagating along a parabolic trajectory. Their traits may be harnessed for applications in materials science, electron microscopy, and interferometry, and so it is important to measure their properties with ease. Here, we show how one may immediately quantify these beams' parameters without need for additional fabrication or nonstandard microscopic tools. Our experimental results are backed by numerical simulations and analytic derivation.

  13. Monitoring Location and Angular Orientation of a Pill

    Science.gov (United States)

    Schipper, John F.

    2012-01-01

    A mobile pill transmitter system moves through, or adjacent to, one or more organs in an animal or human body, while transmitting signals from its present location and/or present angular orientation. The system also provides signals from which the present roll angle of the pill, about a selected axis, can be determined. When the location coordinates angular orientation and the roll angle of the pill are within selected ranges, an aperture on the pill container releases a selected chemical into, or onto, the body. Optionally, the pill, as it moves, provides a sequence of visually perceptible images. The times for image formation may correspond to times at which the pill transmitter system location or image satisfies one of at least four criteria. This invention provides and supplies an algorithm for exact determination of location coordinates and angular orientation coordinates for a mobile pill transmitter (PT), or other similar device that is introduced into, and moves within, a GI tract of a human or animal body. A set of as many as eight nonlinear equations has been developed and applied, relating propagation of a wireless signal between either two, three, or more transmitting antennas located on the PT, to four or more non-coplanar receiving antennas located on a signal receiver appliance worn by the user. The equations are solved exactly, without approximations or iterations, and are applied in several environments: (1) association of a visual image, transmitted by the PT at each of a second sequence of times, with a PT location and PT angular orientation at that time; (2) determination of a position within the body at which a drug or chemical substance or other treatment is to be delivered to a selected portion of the body; (3) monitoring, after delivery, of the effect(s) of administration of the treatment; and (4) determination of one or more positions within the body where provision and examination of a finer-scale image is warranted.

  14. BAO from Angular Clustering: Optimization and Mitigation of Theoretical Systematics

    Energy Technology Data Exchange (ETDEWEB)

    Crocce, M.; et al.

    2018-01-13

    We study the theoretical systematics and optimize the methodology in Baryon Acoustic Oscillations (BAO) detections using the angular correlation function with tomographic bins. We calibrate and optimize the pipeline for the Dark Energy Survey Year 1 dataset using 1800 mocks. We compare the BAO fitting results obtained with three estimators: the Maximum Likelihood Estimator (MLE), Profile Likelihood, and Markov Chain Monte Carlo. The MLE method yields the least bias in the fit results (bias/spread $\\sim 0.02$) and the error bar derived is the closest to the Gaussian results (1% from 68% Gaussian expectation). When there is mismatch between the template and the data either due to incorrect fiducial cosmology or photo-$z$ error, the MLE again gives the least-biased results. The BAO angular shift that is estimated based on the sound horizon and the angular diameter distance agree with the numerical fit. Various analysis choices are further tested: the number of redshift bins, cross-correlations, and angular binning. We propose two methods to correct the mock covariance when the final sample properties are slightly different from those used to create the mock. We show that the sample changes can be accommodated with the help of the Gaussian covariance matrix or more effectively using the eigenmode expansion of the mock covariance. The eigenmode expansion is significantly less susceptible to statistical fluctuations relative to the direct measurements of the covariance matrix because the number of free parameters is substantially reduced [$p$ parameters versus $p(p+1)/2$ from direct measurement].

  15. Metamaterials-based Salisbury screens with reduced angular sensitivity

    Science.gov (United States)

    Wells, Brian M.; Roberts, Christopher M.; Podolskiy, Viktor A.

    2014-10-01

    We demonstrate that the incorporation of nonlocal nanowire metamaterials into Salisbury screens allows for a substantial reduction of the dependence of incident angle on the absorption maximum. Realizations of angle-independent Salisbury screens for the near-IR, mid-IR, and GHz frequencies are proposed and their performances are analyzed analytically and numerically. It is shown that nonlocal effective medium theory adequately describes the angular dependence of nanowire-based Salisbury screens.

  16. Angular momentum coupling in atom-atom collisions

    International Nuclear Information System (INIS)

    Grosser, J.

    1986-01-01

    The coupling between the electronic angular momentum and the rotating atom-atom axis in the initial or the final phase of an atom-atom collision is discussed, making use of the concepts of radial and rotational (Coriolis) coupling between different molecular states. The description is based on a limited number of well-understood approximations, and it allows an illustrative geometric representation of the transition from the body fixed to the space fixed motion of the electrons. (orig.)

  17. Introduction to the graphical theory of angular momentum Case studies

    CERN Document Server

    Balcar, Ewald

    2009-01-01

    Application of quantum mechanics in physics and chemistry often entails manipulation and evaluation of sums and products of coupling coefficients for the theory of angular momentum. Challenges encountered in such work can be tamed by graphical techniques that provide both the insight and analytical power. The book is the first step-by-step exposition of a graphical method grounded in established work. Copious exercises recover standard results but demonstrate the power to go beyond.

  18. Superpositions of light fields carrying orbital angular momentum

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2012-01-01

    Full Text Available OF LIGHT FIELDS CARRYING ORBITAL ANGULAR MOMENTUM By Angela Dudley A thesis submitted in fulfilment of the academic requirements for the PhD degree of Science in the School of Chemistry and Physics, University of KwaZulu-Natal, Durban... this dissertation for submission. _________________________________ Prof Andrew Forbes On this_______day of____________________________2012 iv Declaration 2 - Plagiarism I, ???????????????. declare that 1...

  19. Angular correlation of annihilation photons in frozen aqueous solutions

    DEFF Research Database (Denmark)

    Milosevic-Kvajic, M.; Mogensen, O. E.; Kvajic, G.

    1972-01-01

    Linear‐slit angular correlation curves were obtained at about −140°C for frozen aqueous solutions of HF, HCl, HBr, HI, NH3, FeCl2, FeCl3, NaI, H2SO4, NHO3, MnSO4, KMnO4, K2Cr2O7, NaOH, and LiOH. We found no appreciable influence of a 4% concentration of the last seven impurities. Only halide‐cont...

  20. Differences between Doppler velocities of ions and neutral atoms in a solar prominence

    Science.gov (United States)

    Anan, T.; Ichimoto, K.; Hillier, A.

    2017-05-01

    Context. In astrophysical systems with partially ionized plasma, the motion of ions is governed by the magnetic field while the neutral particles can only feel the magnetic field's Lorentz force indirectly through collisions with ions. The drift in the velocity between ionized and neutral species plays a key role in modifying important physical processes such as magnetic reconnection, damping of magnetohydrodynamic waves, transport of angular momentum in plasma through the magnetic field, and heating. Aims: This paper aims to investigate the differences between Doppler velocities of calcium ions and neutral hydrogen in a solar prominence to look for velocity differences between the neutral and ionized species. Methods: We simultaneously observed spectra of a prominence over an active region in H I 397 nm, H I 434 nm, Ca II 397 nm, and Ca II 854 nm using a high dispersion spectrograph of the Domeless Solar Telescope at Hida observatory. We compared the Doppler velocities, derived from the shift of the peak of the spectral lines presumably emitted from optically-thin plasma. Results: There are instances when the difference in velocities between neutral atoms and ions is significant, for example 1433 events ( 3% of sets of compared profiles) with a difference in velocity between neutral hydrogen atoms and calcium ions greater than 3σ of the measurement error. However, we also found significant differences between the Doppler velocities of two spectral lines emitted from the same species, and the probability density functions of velocity difference between the same species is not significantly different from those between neutral atoms and ions. Conclusions: We interpreted the difference of Doppler velocities as being a result of the motions of different components in the prominence along the line of sight, rather than the decoupling of neutral atoms from plasma. The movie attached to Fig. 1 is available at http://www.aanda.org

  1. How we are building a complex Angular 2 application at Inspire

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    In this talk, at first we will talk about some basic and advanced Angular 2 concepts, then we will share our experiences with Angular 2 that we had so far while building a complex library and web applications at Inspire.

  2. Nuclear level density parameter 's dependence on angular momentum

    International Nuclear Information System (INIS)

    Aggarwal, Mamta; Kailas, S.

    2009-01-01

    Nuclear level densities represent a very important ingredient in the statistical Model calculations of nuclear reaction cross sections and help to understand the microscopic features of the excited nuclei. Most of the earlier experimental nuclear level density measurements are confined to low excitation energy and low spin region. A recent experimental investigation of nuclear level densities in high excitation energy and angular momentum domain with some interesting results on inverse level density parameter's dependence on angular momentum in the region around Z=50 has motivated us to study and analyse these experimental results in a microscopic theoretical framework. In the experiment, heavy ion fusion reactions are used to populate the excited and rotating nuclei and measured the α particle evaporation spectra in coincidence with ray multiplicity. Residual nuclei are in the range of Z R 48-55 with excitation energy range 30 to 40 MeV and angular momentum in 10 to 25. The inverse level density parameter K is found to be in the range of 9.0 - 10.5 with some exceptions

  3. Dual electromagnetism: helicity, spin, momentum and angular momentum

    International Nuclear Information System (INIS)

    Bliokh, Konstantin Y; Nori, Franco; Bekshaev, Aleksandr Y

    2013-01-01

    The dual symmetry between electric and magnetic fields is an important intrinsic property of Maxwell equations in free space. This symmetry underlies the conservation of optical helicity and, as we show here, is closely related to the separation of spin and orbital degrees of freedom of light (the helicity flux coincides with the spin angular momentum). However, in the standard field-theory formulation of electromagnetism, the field Lagrangian is not dual symmetric. This leads to problematic dual-asymmetric forms of the canonical energy–momentum, spin and orbital angular-momentum tensors. Moreover, we show that the components of these tensors conflict with the helicity and energy conservation laws. To resolve this discrepancy between the symmetries of the Lagrangian and Maxwell equations, we put forward a dual-symmetric Lagrangian formulation of classical electromagnetism. This dual electromagnetism preserves the form of Maxwell equations, yields meaningful canonical energy–momentum and angular-momentum tensors, and ensures a self-consistent separation of the spin and orbital degrees of freedom. This provides a rigorous derivation of the results suggested in other recent approaches. We make the Noether analysis of the dual symmetry and all the Poincaré symmetries, examine both local and integral conserved quantities and show that only the dual electromagnetism naturally produces a complete self-consistent set of conservation laws. We also discuss the observability of physical quantities distinguishing the standard and dual theories, as well as relations to quantum weak measurements and various optical experiments. (paper)

  4. Mass and Angular Distributions of Charged Dihadron Production

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, Mary Clare [Michigan U.

    1990-01-01

    Experiment 711, conducted at Fermilab. provided a unique handle towards understanding valence quark scattering by studying pairs of single. charged, high transverse momentum hadrons produced in collisions of 800 GeV /c protons on fixed metal targets. The apparatus consisted of a double-arm spectrometer. calorimetrically triggered. with high momentum resolution and a large angular acceptance for all charge states of particle pairs. The experiment was designed to select those hadron pairs that carrted most of the momentum and energy of the underlying scattered quarks and gluons. The charge of such "leading" hadrons is correlated with the charge of the quark that produced it. Quantum Chromodynamics (QCD) assumes that the scattering behavior of quarks ts independent of their charge, or "flavour": Experiment 711 could test this assumption. Tilis dissertation descrtbes the analysis of the mass and angular distributions of hadron pair production for three separate charge states: +-, ++ and --. The angular distributions are found to deviate from theory predictions of flavour symmetry. Also. the mass cross sections indicate ratios of positive to negative hard-scattered particles that are larger than expected from theory. These results could warrant reconsideration of the assumptions and approximations currently made in leading-order QCD calculations.

  5. Fragment Angular Anisotropies for Magic and Non-Magic Nuclei

    Science.gov (United States)

    Behkami, A. N.; Maroofi, S.; Esmailipour, A.; Rasooli, S.

    2007-10-01

    Fission fragment angular distributions have been studied for ^239 Pu (n, f) reaction at several neutron energies. Theoretical calculations have been utilized to determine the variance K0^2 at each bombarding energy from the observed angular anisotropies. The values of K0^2 show sharp rise from a value of 5-6 to about 13 for higher neutron energies. From the position of one of the breaks in the K0^2 value, the magnitude of the pairing gap 2δ in the highly deformed transition nucleus ^240 Pu is estimated to be 2.4 MeV. Fission fragment angular anisotropies from changed particle fission of ^208 Pb, ^209 Bi, ^235U and ^238U at laboratory energy of 43.0 MeV have also been analyzed using the traditional transition state model. In all these calculations, optical model transmission coefficients with spin-orbit interaction have been used. In the case of magic nuclei, ^208Pb and ^209 Bi it is found that the deduced values of K0^2 are very small as compared to their corresponding values for ^235U and ^238U nuclei. This interpreted as due to shell structure, since significant shell and pairing effects appear for the magic nuclei ^208 Pb and ^209 Bi.

  6. Angular dependence of spin-orbit spin-transfer torques

    KAUST Repository

    Lee, Ki-Seung

    2015-04-06

    In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

  7. Angular power spectrum in publically released ALICE events

    Science.gov (United States)

    Llanes-Estrada, Felipe J.; Muñoz Martinez, Jose L.

    2018-02-01

    We study the particles emitted in the fireball following a Relativistic Heavy Ion Collision with the traditional angular analysis employed in cosmology and earth sciences, producing Mollweide plots of the number and pt distribution of a few actual, publically released ALICE-collaboration events and calculating their angular power spectrum. We also examine the angular spectrum of a simple two-particle correlation. While this may not be the optimal way of analyzing heavy ion data, our intention is to provide a one to one comparison to analysis in cosmology. With the limited statistics at hand, we do not find evidence for acoustic peaks but a decrease of Cl that is reminiscent of viscous attenuation, but subject to a strong effect from the rapidity acceptance which probably dominates (so we also subtract the m = 0 component). As an exercise, we still extract a characteristic Silk damping length (proportional to the square root of the viscosity over entropy density ratio) to illustrate the method. The absence of acoustic-like peaks is also compatible with a crossover from the QGP to the hadron gas (because a surface tension at domain boundaries would effect a restoring force that could have driven acoustic oscillations). Presently we do not understand a depression of the l = 6 multipole strength; perhaps ALICE could reexamine it with full statistics.

  8. Analysis of angular heat conduction in rotary heat regenerators

    Energy Technology Data Exchange (ETDEWEB)

    Reis, M.C.; Sphaier, L.A. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica. Lab. de Mecanica Teorica e Aplicada], Emails: lasphaier@mec.uff.br, marcelloreis@vm.uff.br

    2010-07-01

    Heat regenerators can be found in a considerable number of engineering applications, and are either used as pair of fixed matrices or as single rotary matrix. The thermal design of these devices is usually done considering models that rely on well-established simplifying assumptions. While most of these assumptions comprise reasonable considerations, some of them could lead to noticeable errors on some occasions. One such assumption is that there is no heat transfer between adjacent channels within the regenerator matrix. While this is quite reasonable for fixed-bed exchangers, this might not be a good choice for rotary exchangers on some occasions. Since rotary matrices can operate between two process streams presenting a large temperature difference between them, a large temperature gradient may develop within the plane normal to the flow direction, especially in the angular direction. This paper proposes a new model for simulating rotary heat regenerators, taking into account this previously unconsidered matrix heat conduction effect. A numerical solution of a test case with angular heat conduction is carried-out. With this solution, a parametric analysis is performed, showing how the effects that gradually increasing the angular heat conduction can affect the temperature distributions within the matrix and regenerator outlet. (author)

  9. GR angular momentum in the quadratic spinor Lagrangian formulation

    Science.gov (United States)

    Li, Siao-Jing

    2016-08-01

    We inquire into the question of whether the quadratic spinor Lagrangian (QSL) formulation can describe the angular momentum for a general-relativistic system. The QSL Hamiltonian has previously been shown to be able to yield an energy-momentum quasilocalization which brings a proof of the positive gravitational energy when the spinor satisfies the conformal Witten equation. After inspection, we find that, under the constraint that the spinor on the asymptotic boundary is a constant, the QSL Hamiltonian is successful in giving an angular momentum quasilocalization. We also make certain the spinor in the Hamiltonian plays the role of a gauge field, a warrant of our permission to impose constraints on the spinor. Then, by some adjustment of the QSL Hamiltonian, we gain a covariant center-of-mass moment quasilocalization only under the condition that the displacement on the asymptotic boundary is a Killing boost vector. We expect the spinor expression will bring a proof of some connection between the gravitational energy and angular momentum.

  10. Angular parallelization of a curvilinear Sn transport theory method

    International Nuclear Information System (INIS)

    Haghighat, A.

    1991-01-01

    In this paper a parallel algorithm for angular domain decomposition (or parallelization) of an r-dependent spherical S n transport theory method is derived. The parallel formulation is incorporated into TWOTRAN-II using the IBM Parallel Fortran compiler and implemented on an IBM 3090/400 (with four processors). The behavior of the parallel algorithm for different physical problems is studied, and it is concluded that the parallel algorithm behaves differently in the presence of a fission source as opposed to the absence of a fission source; this is attributed to the relative contributions of the source and the angular redistribution terms in the S s algorithm. Further, the parallel performance of the algorithm is measured for various problem sizes and different combinations of angular subdomains or processors. Poor parallel efficiencies between ∼35 and 50% are achieved in situations where the relative difference of parallel to serial iterations is ∼50%. High parallel efficiencies between ∼60% and 90% are obtained in situations where the relative difference of parallel to serial iterations is <35%

  11. Angular deflection of rotary nickel titanium files: a comparative study

    Directory of Open Access Journals (Sweden)

    Gianluca Gambarini

    2009-12-01

    Full Text Available A new manufacturing method of twisting nickel titanium wire to produce rotary nickel titanium (RNT files has recently been developed. The aim of the present study was to evaluate whether the new manufacturing process increased the angular deflection of RNT files, by comparing instruments produced using the new manufacturing method (Twisted Files versus instruments produced with the traditional grinding process. Testing was performed on a total of 40 instruments of the following commercially available RNT files: Twisted Files (TF, Profile, K3 and M2 (NRT. All instruments tested had the same dimensions (taper 0.06 and tip size 25. Test procedures strictly followed ISO 3630-1. Data were collected and statistically analyzed by means ANOVA test. The results showed that TF demonstrated significantly higher average angular deflection levels (P<0.05, than RNT manufactured by a grinding process. Since angular deflection represent the amount of rotation (and consequently deformation that a RNT file can withstand before torsional failure, such a significant improvement is a favorable property for the clinical use of the tested RNT files.

  12. Angular glint effects generation for false naval target verisimility requirements

    International Nuclear Information System (INIS)

    Kostis, Theodoros G; Galanis, Konstantinos G; Katsikas, Sokratis K

    2009-01-01

    A stimulating problem in the generation of coherent countermeasures for high range resolution radar systems is the inclusion of angular glint effects in the preparation of the false target mask. Since angular glint is representative of extended naval targets, this inclusion increases the credibility factor of the decoy playback signal at the adversary radar-operator station. In this paper, the ability of an interferometric inverse synthetic aperture radar (InISAR) simulator to provide a proof of concept towards the clarification of this challenging task is ascertained. The solution consists of three novel vector representations of the generated data, which are proven to behave according to the laws of physics governing the glint phenomenon. The first depiction is the angular glint injection at the target which is followed by the representation of the wavefront distortion at the radar. A value-added time procession integration of the target in pure roll motion provides an expected by ISAR theory side-view image of the naval extended false target. The effectiveness of the proposed approach through verification and validation of the results by using the method of pictorial evidence is established. A final argument is raised on the usage of this software tool for actual obfuscation and deception actions for air defence at sea applications

  13. Electron velocity and momentum density

    International Nuclear Information System (INIS)

    Perkins, G.A.

    1978-01-01

    A null 4-vector eta + sigma/sub μ/based on Dirac's relativistic electron equation, is shown explicitly for a plane wave and various Coulomb states. This 4-vector constitutes a mechanical ''model'' for the electron in those staes, and expresses the important spinor quantities represented conventionally by n, f, g, m, j, kappa, l, and s. The model for a plane wave agrees precisely with the relation between velocity and phase gradient customarily used in quantum theory, but the models for Coulomb states contradict that relation

  14. Angular filter refractometry analysis using simulated annealing [An improved method for characterizing plasma density profiles using angular filter refractometry

    International Nuclear Information System (INIS)

    Angland, P.; Haberberger, D.; Ivancic, S. T.; Froula, D. H.

    2017-01-01

    Here, a new method of analysis for angular filter refractometry images was developed to characterize laser-produced, long-scale-length plasmas using an annealing algorithm to iterative converge upon a solution. Angular filter refractometry (AFR) is a novel technique used to characterize the density pro files of laser-produced, long-scale-length plasmas. A synthetic AFR image is constructed by a user-defined density profile described by eight parameters, and the algorithm systematically alters the parameters until the comparison is optimized. The optimization and statistical uncertainty calculation is based on a minimization of the χ2 test statistic. The algorithm was successfully applied to experimental data of plasma expanding from a flat, laser-irradiated target, resulting in average uncertainty in the density profile of 5-10% in the region of interest.

  15. Energy and angular dependence of thermoluminescent materials to beta monitoring; Dependencia energetica e angular de materiais termoluminescentes para monitoracao beta

    Energy Technology Data Exchange (ETDEWEB)

    Cecatti, Sonia Garcia Pereira; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo, SP (Brazil)]. E-mail: scecatti@fundacentro.gov.br

    2006-11-15

    Energy and angular dependences of different thermoluminescent materials were studied with the objective to verify which type of detector would be the most appropriate for beta monitoring of workers. Three types of CaSO{sub 4}:Dy + teflon pellets were studied. The energy dependence was evaluated using standard beta radiation sources ({sup 147} Pm, {sup 2}''0{sup 4} Tl and {sup 90} Sr+{sup 90} Y). For the angular dependence study, the pellets were exposed to beta radiation of the {sup 9}'0 Sr+{sup 90} Y source, varying the incidence angle between 0 deg C and 90 deg C. In relation to the studied characteristics, the CaSO{sub 4}:Dy + 10% C dosimeters were the most adequate for use in beta monitoring of workers. (author)

  16. Robust flight control using incremental nonlinear dynamic inversion and angular acceleration prediction

    OpenAIRE

    Sieberling, S.; Chu, Q.P.; Mulder, J.A.

    2010-01-01

    This paper presents a flight control strategy based on nonlinear dynamic inversion. The approach presented, called incremental nonlinear dynamic inversion, uses properties of general mechanical systems and nonlinear dynamic inversion by feeding back angular accelerations. Theoretically, feedback of angular accelerations eliminates sensitivity to model mismatch, greatly increasing the robust performance of the system compared with conventional nonlinear dynamic inversion. However, angular acce...

  17. Angular Random Walk Estimation of a Time-Domain Switching Micromachined Gyroscope

    Science.gov (United States)

    2016-10-19

    TECHNICAL DOCUMENT 3308 September 2016 Angular Random Walk Estimation of a Time-Domain Switching Micromachined Gyroscope Andrew B. Sabater Paul...angular random walk (ARW), bias instability, and scale factor instability. While there are methods to address issues with bias and scale factor...8 4. ANGULAR RANDOM WALK CHARACTERIZATION

  18. Is angular momentum in the horizontal plane during gait a controlled variable?

    NARCIS (Netherlands)

    Thielemans, V.; Meyns, P.; Bruijn, S.M.

    2014-01-01

    It has been suggested that angular momentum in the horizontal plane during human gait is controlled (i.e., kept minimal). However, this has not been explored in conditions when angular momentum of different segments is manipulated explicitly. In order to examine the behavior of angular momentum, 12

  19. Angular kyphosis as an indicator of the prevalence of Pott's disease ...

    African Journals Online (AJOL)

    'rounded' or 'angular'. Rounded kyphosis is common and includes physiological, osteoporotic, postural and. Scheuermann's kyphoses. Angular kyphosis, in contrast, is characterised by an abrupt increase in the dorsal angulation of the spine within the span of a few vertebrae. Angular. Division of Orthopaedics, University of ...

  20. Singularity in the Laboratory Frame Angular Distribution Derived in Two-Body Scattering Theory

    Science.gov (United States)

    Dick, Frank; Norbury, John W.

    2009-01-01

    The laboratory (lab) frame angular distribution derived in two-body scattering theory exhibits a singularity at the maximum lab scattering angle. The singularity appears in the kinematic factor that transforms the centre of momentum (cm) angular distribution to the lab angular distribution. We show that it is caused in the transformation by the…

  1. Premotor neurons encode torsional eye velocity during smooth-pursuit eye movements

    Science.gov (United States)

    Angelaki, Dora E.; Dickman, J. David

    2003-01-01

    Responses to horizontal and vertical ocular pursuit and head and body rotation in multiple planes were recorded in eye movement-sensitive neurons in the rostral vestibular nuclei (VN) of two rhesus monkeys. When tested during pursuit through primary eye position, the majority of the cells preferred either horizontal or vertical target motion. During pursuit of targets that moved horizontally at different vertical eccentricities or vertically at different horizontal eccentricities, eye angular velocity has been shown to include a torsional component the amplitude of which is proportional to half the gaze angle ("half-angle rule" of Listing's law). Approximately half of the neurons, the majority of which were characterized as "vertical" during pursuit through primary position, exhibited significant changes in their response gain and/or phase as a function of gaze eccentricity during pursuit, as if they were also sensitive to torsional eye velocity. Multiple linear regression analysis revealed a significant contribution of torsional eye movement sensitivity to the responsiveness of the cells. These findings suggest that many VN neurons encode three-dimensional angular velocity, rather than the two-dimensional derivative of eye position, during smooth-pursuit eye movements. Although no clear clustering of pursuit preferred-direction vectors along the semicircular canal axes was observed, the sensitivity of VN neurons to torsional eye movements might reflect a preservation of similar premotor coding of visual and vestibular-driven slow eye movements for both lateral-eyed and foveate species.

  2. Dynamical evolution of angular momentum in damped nuclear reactions (I). Accumulation of angular momentum by nucleon transfer

    Science.gov (United States)

    Døssing, Thomas; Randrup, Jørgen

    1985-02-01

    The dynamical accumulation of angular momentum in the course of a damped nuclear reaction is studied within the framework of the nucleon exchange transport model. The dinuclear spin distribution is described by the mean values and the covariances of the two prefragment spins and their orbital angular momentum overlineL. Using an intrinsic coordinate system aligned with the fluctuating direction of overlineL, the equations of motion for the spin distribution are derived and discussed. The ultimate transformation to an externally defined reference frame is also discussed. The evolution of other observables and their coupling to the spin variables are included and, by integrating conditional distributions over all impact parameters, results are obtained for differential cross sections corresponding to a specified loss of relative kinetic energy. The characteristic features of the evolution of the spin distribution is discussed in detail. First the stationary solution of the equations of motion is considered and its different appearance in the various relevant coordinate systems is exhibited. The dynamical evolution is discussed in terms of the time-dependent relaxation times associated with the six different intrinsic modes of rotation in the disphere. Due to the relative smallness of the window size the positive modes will dominate (for not too long times), resulting in a predominantly positive correlation between the fragment spin fluctuations. Illustrative applications to cases of experimental interest are made and a critical discussion is given of other models addressing angular momentum in damped nuclear reactions.

  3. Energy and angular dependence of thermoluminescent materials for beta monitoring; Dependencia energetica e angular de materiais termoluminescentes para monitoracao beta

    Energy Technology Data Exchange (ETDEWEB)

    Cecatti, S.G.P. [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Sao Paulo, SP (Brazil); Caldas, L.V.E. [Instituto de Pesquisas Energeticas e Nucleares, (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2004-07-01

    This work has as objective the study of the energy and angular dependence of different thermoluminescent (TL) materials for an appropriate choice of the material to be used for beta monitoring of workers. Three types of CaSO{sub 4}:Dy + Teflon pellets were studied. The energy dependence was verified using standard sources of beta radiation ({sup 147}Pm, {sup 204}Tl and {sup 90}Sr + {sup 90}Y). For the angular dependence study the pellets were irradiated with beta radiation of the {sup 90}Sr + {sup 90}Y source, varying the incidence angle between 0 deg C and 90 deg C. The CaSO{sub 4}: Dy (50 mg) and of CaSO{sub 4}:Dy (20 mg) pellets presented practically the same high energy dependence, while the CaSO{sub 4}:Dy + 10% C pellets presented a dependence with the energy of 60% in the studied interval. The TL response of the three materials presented an accentuated angular dependence starting from 45 deg C. The dosimeters of CaSO{sub 4}:Dy + 10% C showed to be the most adequate for use in beta monitoring of workers, in relation to the studied characteristics. (author)

  4. Vector blood velocity estimation in medical ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gran, Fredrik; Udesen, Jesper

    2006-01-01

    Two methods for making vector velocity estimation in medical ultrasound are presented. All of the techniques can find both the axial and transverse velocity in the image and can be used for displaying both the correct velocity magnitude and direction. The first method uses a transverse oscillation...... search can also yield the direction, and the full velocity vector is thereby found. An examples from a flow rig is shown....

  5. Extending the unambiguous velocity range using multiple carrier frequencies

    DEFF Research Database (Denmark)

    Zhang, Z.; Jakobsson, A.; Nikolov, Svetoslav

    2005-01-01

    Typically, velocity estimators based on the estimation of the Doppler shift will suffer from a limited unambiguous velocity range. Proposed are two novel multiple carrier based velocity estimators extending the velocity range above the Nyquist velocity limit. Numerical simulations indicate...

  6. 3D shear wave velocity structure revealed with ambient noise tomography on a DAS array

    Science.gov (United States)

    Zeng, X.; Thurber, C. H.; Wang, H. F.; Fratta, D.

    2017-12-01

    An 8700-m Distributed Acoustic Sensing (DAS) cable was deployed at Brady's Hot Springs, Nevada in March 2016 in a 1.5 by 0.5 km study area. The layout of the DAS array was designed with a zig-zag geometry to obtain relatively uniform areal and varied angular coverage, providing very dense coverage with a one-meter channel spacing. This array continuously recorded signals of a vibroseis truck, earthquakes, and traffic noise during the 15-day deployment. As shown in a previous study (Zeng et al., 2017), ambient noise tomography can be applied to DAS continuous records to image shear wave velocity structure in the near surface. To avoid effects of the vibroseis truck operation, only continuous data recorded during the nighttime was used to compute noise cross-correlation functions for channel pairs within a given linear segment. The frequency band of whitening was set at 5 to 15 Hz and the length of the cross-correlation time window was set to 60 second. The phase velocities were determined using the multichannel analysis of surface waves (MASW) methodology. The phase velocity dispersion curve was then used to invert for shear wave velocity profiles. A preliminarily velocity model at Brady's Hot Springs (Lawrence Livermore National Laboratory, 2015) was used as the starting model and the sensitivity kernels of Rayleigh wave group and phase velocities were computed with this model. As the sensitivity kernel shows, shear wave velocity in the top 200 m can be constrained with Rayleigh wave group and phase velocities in our frequency band. With the picked phase velocity data, the shear wave velocity structure can be obtained via Occam's inversion (Constable et al., 1987; Lai 1998). Shear wave velocity gradually increases with depth and it is generally faster than the Lawrence Livermore National Laboratory (2015) model. Furthermore, that model has limiting constraints at shallow depth. The strong spatial variation is interpreted to reflect the different sediments and

  7. Application of Vectors to Relative Velocity

    Science.gov (United States)

    Tin-Lam, Toh

    2004-01-01

    The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…

  8. Questions Students Ask: About Terminal Velocity.

    Science.gov (United States)

    Meyer, Earl R.; Nelson, Jim

    1984-01-01

    If a ball were given an initial velocity in excess of its terminal velocity, would the upward force of air resistance (a function of velocity) be greater than the downward force of gravity and thus push the ball back upwards? An answer to this question is provided. (JN)

  9. Balance velocities of the Greenland ice sheet

    DEFF Research Database (Denmark)

    Joughin, I.; Fahnestock, M.; Ekholm, Simon

    1997-01-01

    We present a map of balance velocities for the Greenland ice sheet. The resolution of the underlying DEM, which was derived primarily from radar altimetery data, yields far greater detail than earlier balance velocity estimates for Greenland. The velocity contours reveal in striking detail......, the balance map is useful for ice-sheet modelling, mass balance studies, and field planning....

  10. Branching ratio and angular distribution of ejected electrons from Eu 4f76p1/2 n d auto-ionizing states

    International Nuclear Information System (INIS)

    Wu Xiao-Rui; Shen Li; Zhang Kai; Dai Chang-Jian; Yang Yu-Na

    2016-01-01

    The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f 7 6p 1/2 n d auto-ionizing states are investigated with the velocity-map-imaging technique. To populate the above auto-ionizing states, the relevant bound Rydberg states have to be detected first. Two new bound Rydberg states are identified in the region between 41150 cm −1 and 44580 cm −1 , from which auto-ionization spectra of the Eu 4f 7 6p 1/2 n d states are observed with isolated core excitation method. With all preparations above, the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically. Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed, followed by a qualitative interpretation. (paper)

  11. The close circumstellar environment of Betelgeuse. V. Rotation velocity and molecular envelope properties from ALMA

    Science.gov (United States)

    Kervella, Pierre; Decin, Leen; Richards, Anita M. S.; Harper, Graham M.; McDonald, Iain; O'Gorman, Eamon; Montargès, Miguel; Homan, Ward; Ohnaka, Keiichi

    2018-01-01

    We observed Betelgeuse using ALMA's extended configuration in band 7 (f ≈ 340 GHz, λ ≈ 0.88 mm), resulting in a very high angular resolution of 18 mas. Using a solid body rotation model of the 28SiO(ν= 2, J = 8-7) line emission, we show that the supergiant is rotating with a projected equatorial velocity of νeqsini = 5.47 ± 0.25 km s-1 at the equivalent continuum angular radius Rstar = 29.50 ± 0.14 mas. This corresponds to an angular rotation velocity of ω sini = (5.6 ± 1.3) × 10-9 rad s-1. The position angle of its north pole is PA = 48.0 ± 3.5°. The rotation period of Betelgeuse is estimated to P/ sini = 36 ± 8 years. The combination of our velocity measurement with previous observations in the ultraviolet shows that the chromosphere is co-rotating with the star up to a radius of ≈ 10 au (45 mas or 1.5 × the ALMA continuum radius). The coincidence of the position angle of the polar axis of Betelgeuse with that of the major ALMA continuum hot spot, a molecular plume, and a partial dust shell (from previous observations) suggests that focused mass loss is currently taking place in the polar region of the star. We propose that this hot spot corresponds to the location of a particularly strong "rogue" convection cell, which emits a focused molecular plume that subsequently condenses into dust at a few stellar radii. Rogue convection cells therefore appear to be an important factor shaping the anisotropic mass loss of red supergiants.

  12. Critical velocities in He II for independently varied superfluid and normal fluid velocities

    International Nuclear Information System (INIS)

    Baehr, M.L.

    1984-01-01

    Experiments were performed to measure the critical velocity in pure superflow and compare to the theoretical prediction; to measure the first critical velocity for independently varied superfluid and normal fluid velocities; and to investigate the propagation of the second critical velocity from the thermal counterflow line through the V/sub n/,-V/sub s/ quadrant. The experimental apparatus employed a thermal counterflow heater to adjust the normal fluid velocity, a fountain pump to vary the superfluid velocity, and a level sensing capacitor to measure the superfluid velocity. The results of the pure superfluid critical velocity measurements indicate that this velocity is temperature independent contrary to Schwarz's theory. It was found that the first critical velocity for independently varied V/sub n/ and V/sub s/ could be described by a linear function of V/sub n/ and was otherwise temperature independent. It was found that the second critical velocity could only be distinguished near the thermal counterflow line

  13. Suppression of angular forces in collisions of non-S-state transition metal atoms

    International Nuclear Information System (INIS)

    Krems, R.V.; Klos, J.; Rode, M.F.; Szczesniak, M.M.; Chalasinski, G.; Dalgarno, A.

    2005-01-01

    Angular momentum transfer is expected to occur rapidly in collisions of atoms in states of nonzero angular momenta due to the large torque of angular forces. We show that despite the presence of internal angular momenta transition metal atoms interact in collisions with helium effectively as spherical atoms and angular momentum transfer is slow. Thus, magnetic trapping and sympathetic cooling of transition metal atoms to ultracold temperatures should be readily achievable. Our results open up new avenues of research with a broad class of ultracold atoms

  14. Unidentified angular recurrent ulceration responsive to antiviral therapy

    Directory of Open Access Journals (Sweden)

    Rahmi Amtha

    2013-03-01

    Full Text Available Background: Recurrent ulcer on angular area is usually called stomatitis angularis. It is caused by many factors such as vertical dimension reduce, vitamin B12, and immune system deficiency, C. albicans and staphylococcus involvement. Clinically is characterized by painful fissure with erythematous base without fever. Purpose: to describe an unidentified angular ulcer proceeded by recurrent ulcers with no response of topical therapy. Case: An 18-years old male came to Oral Medicine clinic in RSCM who complained of angular recurrent ulcers since 3 years ago which developed on skin and bleed easily on mouth opening. Patient had fever before the onset of ulcers. Large, painful, irregular ulcers covered by red crustae on angular area bilaterally. Patient has been treated with various drugs without improvement and lead to mouth opening limitation. Intra oral shows herpetiformtype of ulcer and swollen of gingival. Case management: Provisional diagnosis was established as viral infection thus acyclovir 200 mg five times daily for two weeks and topical anti inflammation gel were administered. Blood test for IgG/IgM of HSV1 and HSV2 were non reactive, however ulceration showed a remarkable improvement. The ulcers healed completely after next 2 weeks with acyclovir. Conclusion: The angular ulceration on above patient failed to fulfill the criteria of stomatitis angularis or herpes labialis lesion. However it showed a good response to antiviral. Therefore, unidentified angular ulceration was appointed, as the lesion might be triggered by other type of human herpes virus or types of virus that response to acyclovir.Latar belakang: ulser rekuren pada sudut mulut biasanya disebut stomatitis angularis. Kelainan ini disebabkan oleh banyak faktor seperti berkurangnya dimensi vertikal, defisiensi vitamin B12 dan sistem kekebalan tubuh, infeksi C. albicans serta staphylococcus. Secara klinis kelainan ini ditandai dengan fisur sakit pada sudut mulut dengan dasar

  15. Deriving High-Precision Radial Velocities

    Science.gov (United States)

    Figueira, Pedro

    This chapter describes briefly the key aspects behind the derivation of precise radial velocities. I start by defining radial velocity precision in the context of astrophysics in general and exoplanet searches in particular. Next I discuss the different basic elements that constitute a spectrograph, and how these elements and overall technical choices impact on the derived radial velocity precision. Then I go on to discuss the different wavelength calibration and radial velocity calculation techniques, and how these are intimately related to the spectrograph's properties. I conclude by presenting some interesting examples of planets detected through radial velocity, and some of the new-generation instruments that will push the precision limit further.

  16. Experimental study of a particle velocity immersed in a fluid in rotation

    International Nuclear Information System (INIS)

    Cesar, S.B.G.

    1981-12-01

    An incompressible viscous fluid is confined within a circular cylinder whose wall and top are fixed while the botton rotates with constant angular speed. The velocity components of a particule immersed in the fluid above, was determined. The method utilized employs filming the particle during its motion. Experimental measurements were made at rotational speeds between 50 and 190 rps, at inter-disc spacing between 10 and 40 cm, and the particle is let loose at distances between static disc and 5 cm above the inferior disc. The results show that the method utilized is valid in a radial region within the cylinder between 1.0 [pt

  17. Dissociative electron attachment to CO molecule probed by velocity slice imaging technique

    Science.gov (United States)

    Nag, Pamir; Nandi, Dhananjay

    2017-11-01

    We have studied dissociative electron attachment to CO molecule using the well-established velocity slice imaging spectrometer. We have conclusively determined the symmetries of the TNI states involved in both the channels producing O‑ ions. In contrast to a recent report, we observed additional forwards lobes in the angular distribution data and we claim there is no need to invoke coherent interference between different states as introduced previously. Recent R-matrix calculations and momentum imaging study by other groups strongly support our claims.

  18. Spin O decay angular distribution for interfering mesons in electroproduction

    Energy Technology Data Exchange (ETDEWEB)

    Funsten, H.; Gilfoyle, G.

    1994-04-01

    Self analyzing meson electroproduction experiments are currently being planned for the CEBAF CLAS detector. These experiments deduce the spin polarization of outgoing unstable spin s (?)0 mesons from their decay angular distribution, W({theta},{psi}). The large angular acceptance of the CLAS detector permits kinematic tracking of a sufficient number of these events to accurately determine electroproduction amplitudes from the deduced polarization. Maximum polarization information is obtained from W({theta},{psi}) for decay into spin 0 daughters. The helicity of the decaying meson is transferred to the daughter`s relative orbital angular momentum m-projection; none is {open_quotes}absorbed{close_quotes} into daughter helicities. The decaying meson`s helicity maximally appears in W({theta},{psi}). W({theta},{psi}) for spin 0 daughters has been derived for (1) vector meson electroproduction and (2) general interfering mesons produced by incident pions. This paper derives W({theta},{psi}) for electroproduction of two interfering mesons that decay into spin 0 daughters. An application is made to the case of interfering scalar and vector mesons. The derivation is an extension of work by Schil using the general decay formalism of Martin. The expressions can be easily extended to the case of N interfering mesons since interference occurs pairwise in the observable W ({theta},{psi}), a quadratic function of the meson amplitudes. The derivation uses the virtual photon density matrix of Schil which is transformed by a meson electroproduction transition operator, T. The resulting density matrix for the interfering mesons is then converted into a corresponding statistical tensor and contracted into the efficiency tensor for spin 0 daughters.

  19. Biocontrole da mancha-angular do feijoeiro por antagonistas bacterianos

    Directory of Open Access Journals (Sweden)

    Flávio Augusto de Oliveira Garcia

    2011-12-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de isolados de Bacillus cereus e Pseudomonas putida sobre a severidade da mancha-angular do feijoeiro, em condições de campo. Quatro experimentos foram conduzidos em épocas favoráveis à mancha-angular (Pseudocercospora griseola, com as cultivares Pérola e Ouro Negro. Os experimentos foram realizados em delineamento de blocos ao acaso, com seis repetições. Os tratamentos foram pulverizações sobre as plantas com três estirpes de B. cereus (UFV-172, UFV-101 e UFV-75 e duas estirpes de P. putida (UFV-53 e UFV-Pp, acibenzolar-S-metil, fungicida clorotalonil e controle pulverizado com água, no total de oito tratamentos. Os tratamentos foram aplicados por atomização no filoplano de plantas de feijoeiro, semanalmente, a partir do 15º dia após a emergência até o fim do ensaio. Calculou-se a área abaixo da curva de progresso da mancha-angular do feijoeiro; a doença ocorreu naturalmente. A produção foi avaliada pela massa média de sementes por planta. Os antagonistas foram eficientes em reduzir a severidade da doença, em comparação à testemunha, e obtiveram o mesmo nível de controle do tratamento químico. O menor índice de severidade da doença propiciou melhor produção do que o tratamento controle.

  20. Electron with orbital angular momentum in a strong laser wave

    Science.gov (United States)

    Karlovets, Dmitry V.

    2012-12-01

    Electrons carrying orbital angular momentum (OAM) have recently been discovered theoretically and obtained experimentally, which opens up possibilities for using them in high-energy physics. We consider such a twisted electron moving in the external field of a plane electromagnetic wave and study how this field influences the electron's OAM. Being motivated by the development of high-power lasers, we focus our attention on a classically strong-field regime for which -e2A2¯/(me2c4)≳1. It is shown that, along with the well-known “plane-wave” Volkov solution, the Dirac equation also has the “non-plane-wave” solutions, which possess OAM and spin-orbit coupling and generalize the free-electron's Bessel states. Motion of an electron with OAM in a circularly polarized laser wave reveals a twofold character: the wave-packet center moves along a classical helical trajectory with some quantum transverse broadening (due to OAM) existing even for a free electron. Using the twisted states, we calculate the electron's total angular momentum and predict its shift in the strong-field regime, which is analogous to the well-known shifts of the electron's momentum and mass (and to a less-known shift of its spin) in intense fields. Since the electron's effective angular momentum is conserved in a plane wave, as well as in some more general field configurations, we discuss several possibilities for accelerating nonrelativistic twisted electrons by using focused and combined electromagnetic fields.

  1. Spin O decay angular distribution for interfering mesons in electroproduction

    International Nuclear Information System (INIS)

    Funsten, H.; Gilfoyle, G.

    1994-01-01

    Self analyzing meson electroproduction experiments are currently being planned for the CEBAF CLAS detector. These experiments deduce the spin polarization of outgoing unstable spin s (?)0 mesons from their decay angular distribution, W(θ,ψ). The large angular acceptance of the CLAS detector permits kinematic tracking of a sufficient number of these events to accurately determine electroproduction amplitudes from the deduced polarization. Maximum polarization information is obtained from W(θ,ψ) for decay into spin 0 daughters. The helicity of the decaying meson is transferred to the daughter's relative orbital angular momentum m-projection; none is open-quotes absorbedclose quotes into daughter helicities. The decaying meson's helicity maximally appears in W(θ,ψ). W(θ,ψ) for spin 0 daughters has been derived for (1) vector meson electroproduction and (2) general interfering mesons produced by incident pions. This paper derives W(θ,ψ) for electroproduction of two interfering mesons that decay into spin 0 daughters. An application is made to the case of interfering scalar and vector mesons. The derivation is an extension of work by Schil using the general decay formalism of Martin. The expressions can be easily extended to the case of N interfering mesons since interference occurs pairwise in the observable W (θ,ψ), a quadratic function of the meson amplitudes. The derivation uses the virtual photon density matrix of Schil which is transformed by a meson electroproduction transition operator, T. The resulting density matrix for the interfering mesons is then converted into a corresponding statistical tensor and contracted into the efficiency tensor for spin 0 daughters

  2. Angular momentum and torque described with the complex octonion

    International Nuclear Information System (INIS)

    Weng, Zi-Hua

    2014-01-01

    The paper aims to adopt the complex octonion to formulate the angular momentum, torque, and force etc in the electromagnetic and gravitational fields. Applying the octonionic representation enables one single definition of angular momentum (or torque, force) to combine some physics contents, which were considered to be independent of each other in the past. J. C. Maxwell used simultaneously two methods, the vector terminology and quaternion analysis, to depict the electromagnetic theory. It motivates the paper to introduce the quaternion space into the field theory, describing the physical feature of electromagnetic and gravitational fields. The spaces of electromagnetic field and of gravitational field can be chosen as the quaternion spaces, while the coordinate component of quaternion space is able to be the complex number. The quaternion space of electromagnetic field is independent of that of gravitational field. These two quaternion spaces may compose one octonion space. Contrarily, one octonion space can be separated into two subspaces, the quaternion space and S-quaternion space. In the quaternion space, it is able to infer the field potential, field strength, field source, angular momentum, torque, and force etc in the gravitational field. In the S-quaternion space, it is capable of deducing the field potential, field strength, field source, current continuity equation, and electric (or magnetic) dipolar moment etc in the electromagnetic field. The results reveal that the quaternion space is appropriate to describe the gravitational features, including the torque, force, and mass continuity equation etc. The S-quaternion space is proper to depict the electromagnetic features, including the dipolar moment and current continuity equation etc. In case the field strength is weak enough, the force and the continuity equation etc can be respectively reduced to that in the classical field theory

  3. Locking of intrinsic angular momentum in collision complexes

    International Nuclear Information System (INIS)

    Berengolts, Alexander.

    1995-04-01

    A concept of locking of the intrinsic angular momentum of a fragment of a collision complex to a body-fixed axis is widely used in the description of heavy-particle dynamics. The aim of this work is to provide a semiclassical description of the locking phenomenon which occur in diatomic and three atomic collision complexes. The first part of this work is devoted to the semiclassical study of the locking of the electronic angular momentum that occurs in slow collisions of two atoms, one in the spherically symmetric state and the other in state with j= 1. Here we calculate explicitly the complete locking matrix for different types of interatomic interactions. The elements of this matrix directly enter into the semiclassical expression for the different cross sections of polarized atoms. Limitations to the notion of the the locking radius and slipping probability are discussed in connection with the steepness of the interaction. Numerical calculations confirm analytical result: the optimal criterion for determination of the locking radius is a condition for the accumulated phase difference between two molecular states. Analytical expressions are suggested for the locking angle and the slipping probability. Implication of the locking approximation for calculation of the quasiclassical scattering matrix is discussed. The second part considers the locking of the rotational angular momentum of a diatom in the decomposition of a triatomic complexes. We discuss here cases J = 1,2,3 and 4, but restrict ourselves to calculation of the so-called dynamic orientation of the diatomic fragment. The letter represents one of the characteristics of the locking matrix which in principle can be measured experimentally. The orientation is created as a result of the interplay between the adiabatic interaction in the atom- diatom exit channel and the rotationally non adiabatic coupling in the perturbed rotor region

  4. Combined calculi for photon orbital and spin angular momenta

    Science.gov (United States)

    Elias, N. M.

    2014-08-01

    Context. Wavelength, photon spin angular momentum (PSAM), and photon orbital angular momentum (POAM), completely describe the state of a photon or an electric field (an ensemble of photons). Wavelength relates directly to energy and linear momentum, the corresponding kinetic quantities. PSAM and POAM, themselves kinetic quantities, are colloquially known as polarization and optical vortices, respectively. Astrophysical sources emit photons that carry this information. Aims: PSAM characteristics of an electric field (intensity) are compactly described by the Jones (Stokes/Mueller) calculus. Similarly, I created calculi to represent POAM characteristics of electric fields and intensities in an astrophysical context. Adding wavelength dependence to all of these calculi is trivial. The next logical steps are to 1) form photon total angular momentum (PTAM = POAM + PSAM) calculi; 2) prove their validity using operators and expectation values; and 3) show that instrumental PSAM can affect measured POAM values for certain types of electric fields. Methods: I derive the PTAM calculi of electric fields and intensities by combining the POAM and PSAM calculi. I show how these quantities propagate from celestial sphere to image plane. I also form the PTAM operator (the sum of the POAM and PSAM operators), with and without instrumental PSAM, and calculate the corresponding expectation values. Results: Apart from the vector, matrix, dot product, and direct product symbols, the PTAM and POAM calculi appear superficially identical. I provide tables with all possible forms of PTAM calculi. I prove that PTAM expectation values are correct for instruments with and without instrumental PSAM. I also show that POAM measurements of "unfactored" PTAM electric fields passing through non-zero instrumental circular PSAM can be biased. Conclusions: The combined PTAM calculi provide insight into mathematically modeling PTAM sources and calibrating POAM- and PSAM-induced measurement errors.

  5. Analysis of angular reading distortions of photographic images.

    Science.gov (United States)

    Codarin, Gabriela F; Felicio, Lilian R; Coelho, Daniel M; Oliveira, Anamaria S

    2012-01-01

    Although photogrammetry is a widespread technique in the health field, despite of the methodological efforts distortions in the angular readings of the images are common. To measure the error of angular measurements in photo images with different digital resolutions in an object with pre-determined angles. We used a rubber ball with 52 cm in circumference. The object was previously marked with angles of 10°, 30°, 60° and 90° degrees. The photographic records were performed with the focal axis of the camera perpendicular and three meters away from the object, without the use of optical zoom and a resolution of 3, 5 and 10 Megapixels (Mp). All photographic records were stored and a previously trained experimenter using the computer program ImageJ analyzed the angular values of each photo. The measurements were performed twice within a fifteen-days interval. Subsequently, we calculated the accuracy, relative error and error in degrees values, precision and the Intraclass Correlation Coefficient (ICC). When analyzing the angle of 10°, the average accuracy of measurements was higher for those records of 3 Mp resolution compared to 5 and 10 Mp resolutions. The ICC was considered excellent for all resolutions. With regards to the analyzed angles in photographic records, it was possible to verify that the 90-degree angle photographs were more accurate, had lower relative error and error in degrees, and were more precise, regardless of image resolution. The photographs records that were taken with a 3 Mp resolution provided great accuracy and precision measurements and lower errors values, suggesting to be the proper resolution to generate image of angles of 10º and 30º.

  6. Calculation of photodetachment cross sections and photoelectron angular distributions of negative ions using density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuan [Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Ning, Chuangang, E-mail: ningcg@tsinghua.edu.cn [Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2015-10-14

    Recently, the development of photoelectron velocity map imaging makes it much easier to obtain the photoelectron angular distributions (PADs) experimentally. However, explanations of PADs are only qualitative in most cases, and very limited works have been reported on how to calculate PAD of anions. In the present work, we report a method using the density-functional-theory Kohn-Sham orbitals to calculate the photodetachment cross sections and the anisotropy parameter β. The spherical average over all random molecular orientation is calculated analytically. A program which can handle both the Gaussian type orbital and the Slater type orbital has been coded. The testing calculations on Li{sup −}, C{sup −}, O{sup −}, F{sup −}, CH{sup −}, OH{sup −}, NH{sub 2}{sup −}, O{sub 2}{sup −}, and S{sub 2}{sup −} show that our method is an efficient way to calculate the photodetachment cross section and anisotropy parameter β for anions, thus promising for large systems.

  7. The critical velocity in swimming.

    Science.gov (United States)

    di Prampero, Pietro E; Dekerle, Jeanne; Capelli, Carlo; Zamparo, Paola

    2008-01-01

    In supra-maximal exercise to exhaustion, the critical velocity (cv) is conventionally calculated from the slope of the distance (d) versus time (t) relationship: d = I + St. I is assumed to be the distance covered at the expense of the anaerobic capacity, S the speed maintained on the basis of the subject's maximal O(2) uptake (VO2max) This approach is based on two assumptions: (1) the energy cost of locomotion per unit distance (C) is constant and (2) VO2max is attained at the onset of exercise. Here we show that cv and the anaerobic distance (d (anaer)) can be calculated also in swimming, where C increases with the velocity, provided that VO2max its on-response, and the C versus v relationship are known. d (anaer) and cv were calculated from published data on maximal swims for the four strokes over 45.7, 91.4 and 182.9 m, on 20 elite male swimmers (18.9 +/- 0.9 years, 75.9 +/- 6.4 kg), whose VO2max and C versus speed relationship were determined, and compared to I and S obtained from the conventional approach. cv was lower than S (4, 16, 7 and 11% in butterfly, backstroke, breaststroke and front crawl) and I (=11.6 m on average in the four strokes) was lower than d (anaer). The latter increased with the distance: average, for all strokes: 38.1, 60.6 and 81.3 m over 45.7, 91.4 and 182.9 m. It is concluded that the d versus t relationship should be utilised with some caution when evaluating performance in swimmers.

  8. Movement velocity vs. strength training

    Directory of Open Access Journals (Sweden)

    Mário C. Marques

    2017-06-01

    practice in strength training, but increasing evidence (Sanborn et al., 2000; Folland et al., 2002; Izquierdo et al., 2006; Drinkwater et al., 2007 shows that training to repetition failure does not necessarily produce better strength gains and that may even be counterproductive by inducing excessive fatigue, mechanical and metabolic strain (Fry, 2004. In fact, fatigue associated with training to failure not only significantly reduces the force that a muscle can generate, but also the nervous system’s ability to voluntarily activate the muscles (Häkkinen, 1993. Consequently, this approach, besides being very tiring and having shown no advantage over other lower effort types of training, it is unrealistic because it is practically impossible to know exactly how many repetitions can be done with a given absolute load without any initial reference. In addition, if in the first set the subject has completed the maximum number of repetitions, it will be very difficult or even impossible to perform properly the same number of reps in the following sets. Movement velocity is another variable which could be of great interest for monitoring exercise intensity, but surprisingly it has been vaguely mentioned in most studies to date. The importance that monitoring movement velocity for strength training programming have already been noticed in 1991 (González-Badillo, 1991. More recently, González-Badillo and Sánchez-Medina (2010, 2011 studied this hypothesis and confirmed that movement velocity provides as a determinant of the level of effort during resistance training as well as an indicator of the degree of fatigue. Unfortunately, the lack of use of this variable is likely because until recently it was not possible to accurately measure velocity in isoinertial strength training exercises/movements.  Indeed, most research that has addressed movement velocity in strength training was basically conducted using isokinetic apparatus which, unfortunately, is not an ideal or common

  9. Angularly-selective transmission imaging in a scanning electron microscope.

    Science.gov (United States)

    Holm, Jason; Keller, Robert R

    2016-08-01

    This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed. Published by Elsevier B.V.

  10. Angular momentum dependence of the nuclear level density parameter

    International Nuclear Information System (INIS)

    Aggarwal, Mamta; Kailas, S.

    2010-01-01

    Dependence of nuclear level density parameter on the angular momentum and temperature is investigated in a theoretical framework using the statistical theory of hot rotating nuclei. The structural effects are incorporated by including shell correction, shape, and deformation. The nuclei around Z≅50 with an excitation energy range of 30 to 40 MeV are considered. The calculations are in good agreement with the experimentally deduced inverse level density parameter values especially for 109 In, 113 Sb, 122 Te, 123 I, and 127 Cs nuclei.

  11. Measurements of electron density profiles using an angular filter refractometer

    Energy Technology Data Exchange (ETDEWEB)

    Haberberger, D., E-mail: dhab@lle.rochester.edu; Ivancic, S.; Hu, S. X.; Boni, R.; Barczys, M.; Craxton, R. S.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14636 (United States)

    2014-05-15

    A novel diagnostic technique, angular filter refractometry (AFR), has been developed to characterize high-density, long-scale-length plasmas relevant to high-energy-density physics experiments. AFR measures plasma densities up to 10{sup 21} cm{sup −3} with a 263-nm probe laser and is used to study the plasma expansion from CH foil and spherical targets that are irradiated with ∼9 kJ of ultraviolet (351-nm) laser energy in a 2-ns pulse. The data elucidate the temporal evolution of the plasma profile for the CH planar targets and the dependence of the plasma profile on target radius for CH spheres.

  12. Perturbed angular correlations at ISOLDE: A 40 years young technique

    Science.gov (United States)

    Schell, Juliana; Schaaf, Peter; Lupascu, Doru C.

    2017-10-01

    The idea that "new-is-small" is a paradigm propelling industries and research: new materials for new applications and new technologies. Precise and efficient characterization techniques are, therefore, required to make the "new" and the "small", understandable, applicable, and reliable. Within this concept, Time Differential Perturbed Angular Correlations, TDPAC, appears as one of the most exotic and efficient techniques to characterize materials and is celebrating 40 years at ISOLDE, CERN. In this overview we explore the TDPAC measurement possibilities at ISOLDE-CERN for solid state physics research with a rich potential due to the wide number of available radioactive probe elements, delivered with great purity and high yield.

  13. Unitarity bounds on angular distribution in multiparticle production - II

    International Nuclear Information System (INIS)

    Divakaran, P.P.; Kugler, M.; Soffer, J.

    1976-01-01

    Upper bounds which follow from unitarity are derived for the angular distribution of the detected particle C in the inclusive process AB→C+anything at a finite energy, in terms of the corresponding elastic amplitudes for a fixed value of the forward inelastic cross-section and for a fixed value of the total inelastic cross-section for the production of C. In comparison with the pp→p+anything data at 24GeV/c, some improvement on previous bounds is observed [fr

  14. High angular resolution diffusion imaging with stimulated echoes

    DEFF Research Database (Denmark)

    Lundell, Henrik; Alexander, Daniel C; Dyrby, Tim B

    2014-01-01

    Stimulated echo acquisition mode (STEAM) diffusion MRI can be advantageous over pulsed-gradient spin-echo (PGSE) for diffusion times that are long compared with T2 . It therefore has potential for biomedical diffusion imaging applications at 7T and above where T2 is short. However, gradient pulses...... angular resolution diffusion imaging (HARDI) data were acquired with and without the proposed compensation. The data were processed to derive standard diffusion tensor imaging (DTI) maps, which highlight the need for the compensation. Ignoring the other gradient pulses, a bias in DTI parameters from STEAM...

  15. Controlled angular redirection of light via nanoimprinted disordered gratings

    DEFF Research Database (Denmark)

    Buss, Thomas; Teisseire, Jérémie; Mazoyer, Simon

    2013-01-01

    Enhanced control of diffraction through transparent substrates is achieved via disordered gratings in a silica sol–gel film. Tailoring the degree of disorder allows tuning of the diffractive behavior from discrete orders into broad distributions over large angular range. Gratings of optical quality...... are formed by silica sol–gel nanoimprint lithography and an optical setup for the measurement of continuous diffraction patterns is presented. Sound agreement is found between measurements and simulation, validating both the approach for redirection of light and the fabrication process. The disordered...

  16. The limit of grain refinement on equal channel angular deformation

    International Nuclear Information System (INIS)

    Kopylov, V.I.; Chuvil'deev, V.N.

    2004-01-01

    Experimental and theoretical study results on the process of strain-induced grain refinement under severe plastic deformation are described. A generalization is made for experimental results on deformation dispersing of copper, magnesium and aluminium base alloys as well as unalloyed metals. The model is developed which allows calculating the minimal grain size being able to result from equal channel angular pressing. The expressions describing the dependence of the limit of grain refinement on the nature of the material and severe plastic deformation rate and temperature are obtained [ru

  17. Measurements of the angular distribution of diffuse irradiance

    DEFF Research Database (Denmark)

    Andersen, Elsa; Nielsen, Kristian Pagh; Dragsted, Janne

    2015-01-01

    Advanced solar resource assessment and forecasting is necessary for optimal solar energy utilization. In order to investigate the short-term resource variability, for instance caused by clouds it is necessary to investigate how clouds affect the solar irradiance, including the angular distribution...... of the solar irradiance. The investigation is part of the Danish contribution to the taskforce 46 within the International Energy Agency and financed by the Danish Energy Agency. The investigation focuses on the distribution of the diffuse solar irradiance and is based on horizontal measurements of the solar...

  18. Influences of preload on the friction and wear properties of high-speed instrument angular contact ball bearings

    Directory of Open Access Journals (Sweden)

    Tao ZHANG

    2018-03-01

    Full Text Available For starved-oil or solid lubrication of high-speed instrument angular contact ball bearings, friction heating and wear are the main reasons of bearing failures. This paper presents a dynamic wear simulation model to investigate the impacts of different preload methods and the changes of preload caused by wear on bearing wear life. The integral value QV of stress and sliding velocity in the contact ellipses between a ball and the inner and outer races determines friction heating and wear. The changes of QV with the friction coefficient and the wear volume under constant-force preload and fixed-position preload are analyzed. Results show that under the same initial preload, the QV decreases with an increase of the friction coefficient for both preload methods, and the latter is slightly larger. The wear of the ball and the race is equivalent to the ball diameter reduction. The QV of constant-force preload is almost not changed with a decrease of the ball diameter, but for fixed-position preload, the value decreases firstly and then increases substantially due to insufficient preload, and slipping occurs, the ball diameter is reduced by 0.025%, while the preload is reduced by 60.33%. An estimation of the bearing wear life under different preload methods requires a consideration of the changes in the wear rate of bearing parts. Keywords: Angular contact ball bearings, Bearing life, Dynamic model, Preload methods, Wear rate

  19. Angular distributions for the inelastic scattering of NO(X2Π ) with O2(X3Σg-)

    Science.gov (United States)

    Brouard, M.; Gordon, S. D. S.; Nichols, B.; Squires, E.; Walpole, V.; Aoiz, F. J.; Stolte, S.

    2017-05-01

    The inelastic scattering of NO(X2Π ) by O2(X3Σg-) was studied at a mean collision energy of 550 cm-1 using velocity-map ion imaging. The initial quantum state of the NO(X2Π , v = 0, j = 0.5, Ω =0.5 , 𝜖 = -1 , f) molecule was selected using a hexapole electric field, and specific Λ-doublet levels of scattered NO were probed using (1 +1' ) resonantly enhanced multiphoton ionization. A modified "onion-peeling" algorithm was employed to extract angular scattering information from the series of "pancaked," nested Newton spheres arising as a consequence of the rotational excitation of the molecular oxygen collision partner. The extracted differential cross sections for NO(X) f →f and f →e Λ-doublet resolved, spin-orbit conserving transitions, partially resolved in the oxygen co-product rotational quantum state, are reported, along with O2 fragment pair-correlated rotational state population. The inelastic scattering of NO with O2 is shown to share many similarities with the scattering of NO(X) with the rare gases. However, subtle differences in the angular distributions between the two collision partners are observed.

  20. Preequilibrium GDR excitation and entrance channel angular momentum effects

    International Nuclear Information System (INIS)

    Sandoli, M.; Campajola, L.; De Rosa, A.; D'Onofrio, A.; La Commara, M.; Ordine, A.; Pierroutsakou, D.; Roca, V.; Romano, M.; Romoli, M.; Terrasi, F.; Trotta, M.; Cardella, G.; Papa, M.; Pappalardo, G.; Rizzo, F.; Alamanos, N.; Auger, F.; Gillibert, A.

    1997-01-01

    The energy spectra of the γ-rays emitted in the 35 Cl+ 92 Mo reaction at incident energy E=260 MeV were measured in coincidence with the ejectiles produced in dissipative reaction events. The cumulative energy spectrum of the γ-rays coming from the decay of the ejectiles was calculated within the statistical model and its comparison to the experimental spectrum evidences an excess in the data for E γ =8 to 12 MeV. Such an excess, fitted with a Lorentz curve, is attributed to the preequilibrium GDR γ-decay of the intermediate dinuclear system. The centroid energy of the Lorentz curve corresponds to a dipole oscillation along the symmetry axis of the system and its width is found to be comparable to that of the ground state GDR low energy component of the deformed dinucleus. The small quantal dispersion Δl=(10.3±0.1)ℎ of the entrance channel angular momentum, determined by analysing the dissipative fragment angular distribution in the framework of the Strutinsky model, is suggested to limit the broadening of the preequilibrium GDR width. (orig.)

  1. ELECTRON ANGULAR DISTRIBUTIONS IN DISSOCIATIVE PHOTOIONIZATION OF THE HYDROGEN MOLECULE.

    Directory of Open Access Journals (Sweden)

    Jhon F. Pérez-Torres

    2009-06-01

    Full Text Available Se propone un método para calcular distribuciones angulares de electrones ionizados en la molécula de hidrógeno fija en el espacio sometida a pulsos láser intensos y ultracortos, basado en la solución desde primeros principios de la ecuación de Schrödinger dependiente del tiempo. Esta solución nos permite tener una visión temporal de la interferencias generadas en el canal de ionización disociativa (en el espectro de energía cinética de los protones debido a la presencia de la autoionización de estados doblemente excitados de la molécula de hidrógeno. Se muestra específicamente cómo la autoionización durante el proceso de fotoionización disociativa también puede inducir una asimetría en la distribución angular del electrón ionizado con respecto a la inversión nuclear, un efecto no intuitivo a pesar de estar tratando con un sistema homonuclear. 

  2. Phoenix II energy extraction and angular multiplexing experiments

    International Nuclear Information System (INIS)

    Hoffman, J.M.; Hays, G.N.

    1981-08-01

    The energy extraction efficiency as a function of input intensity has been determined from a large-volume HF amplifier. For an input intensity of 4 x 10 6 W/cm 2 , 1080 Joules was extracted from the amplifier. This corresponded to an energy extraction efficiency of 0.90. At the highest H 2 /F 2 /O 2 pressures used, 1700 Joules was obtained from this system when used in an oscillator configuration. These results also show evidence that energy extraction at low input intensities in large-volume HF amplifiers is strongly influenced by parasitic oscillations. The results also indicate that, for a long-pulse HF amplifier (60-nsec electron beam), the timing between the amplifier and oscillator to achieve optimum operating conditions is not very critical. This same amplifier, used in conjunction with a short-pulse, good-beam-quality oscillator-preamplifier chain, has also been used to evaluate pulse compression using angular multiplexing. Using two sequential 24-nsec pulses, the essential elements of angular multiplexing have been evaluated as a function of interpulse separation time. Included are energy extraction efficiency, overall temporal pulse distortion, leading-edge contrast-ratio distortion, and suppression of amplified spontaneous emission relative to a single, long-duration input pulse. For appropriate interpulse delay time, we show that distortionless amplification is possible with energy-extraction efficiency the same as is obtained using a single input beam having a pulse width equal to the duration of the amplifier gain

  3. Particle field diagnose using angular multiplexing volume holography

    Science.gov (United States)

    Zhao, Yu; Li, Zeren; Luo, Zhenxiong; Jun, Li; Zhong, Jie; Ye, Yan; Li, Shengfu; Zhu, Jianhua

    2017-08-01

    The problem of particle field diagnosing using holography can be met in many areas. But single frame hologram can only catch one moment of the fast event, which can't reveal the change process of an unrepeatable fast event. For events in different time-scale, different solution should be used. We did this work to record a laser induced particle field in the time-scale of tens of micron seconds. A laser of pulse sequence mode is applied to provide 10 pulses, the energy and time interval of whom is 150mJ and 1μs. Four pockels cells are employed to pick up the last four pulses for holographic recording, the other pulses are controlled to pre-expose the photopolymer based recording material, which can enhance photosensitivity of the photopolymer during the moment of holographic recording. The angular multiplexing technique and volume holography is accepted to avoid shifting the photopolymer between each shot. Another Q-switch YAG laser (pulse energy 100mJ, pulse width 10ns) is applied to produce the fast event. As a result, we successfully caught the motion process of the laser induced particle field. The time interval of each frame is 1μs, the angular range of the four references is 14°, and the diffraction efficiency of each hologram is less than 2%. After a basic analysis, this optical system could catch more holograms through a compact design.

  4. Ion angular distribution simulation of the HEMP Thruster

    Science.gov (United States)

    Duras, Julia; Koch, Norbert; Kahnfeld, Daniel; Bandelow, Gunnar; Matthias, Paul; Lüskow, Karl Felix; Schneider, Ralf; Kemnitz, Stefan

    2016-10-01

    Ion angular current and energy distributions are important parameters for ion thrusters, which are typically measured at a few tens of centimetres to a few meters distance from thruster exit. However, fully kinetic Particle-in-Cell simulations are not able to simulate such domain sizes, due to high computational costs. Therefore, a parallelisation strategy of the code is presented to reduce computational time. To map diagnostics information from the domain boundary of the calculational domain to the positions of experimental diagnostics the concept of transfer functions is introduced. The calculated ion beam angular distributions in the plume region are quite sensitive to boundary conditions of the potential, possible additional source contributions, e.g. from secondary electron emission at vessel walls, and charge exchange collisions. This work was supported by the Bavarian State Ministry of Education Science and the Arts and the German Space Agency DLR. We also like to thank R. Heidemann from THALES Electron Devices GmbH, for interesting and stimulating discussions.

  5. Angular distribution in the neutron-induced fission of actinides

    Directory of Open Access Journals (Sweden)

    Leong L.S.

    2013-12-01

    Full Text Available Above 1 MeV of incident neutron energy the fission fragment angular distribution (FFAD has generally a strong anisotropic behavior due to the combination of the incident orbital momentum and the intrinsic spin of the fissioning nucleus. This effect has to be taken into account for the efficiency estimation of devices used for fission cross section measurements. In addition it bears information on the spin deposition mechanism and on the structure of transitional states. We designed and constructed a detection device, based on Parallel Plate Avalanche Counters (PPAC, for measuring the fission fragment angular distributions of several isotopes, in particular 232Th. The measurement has been performed at n_TOF at CERN taking advantage of the very broad energy spectrum of the neutron beam. Fission events were recognized by back to back detection in coincidence in two position-sensitive detectors surrounding the targets. The detection efficiency, depending mostly on the stopping of fission fragments in backings and electrodes, has been computed with a Geant4 simulation and validated by the comparison to the measured case of 235U below 3 keV where the emission is isotropic. In the case of 232Th, the result is in good agreement with previous data below 10 MeV, with a good reproduction of the structures associated to vibrational states and the opening of second chance fission. In the 14 MeV region our data are much more accurate than previous ones which are broadly scattered.

  6. Neutron angular distribution in plutonium-240 spontaneous fission

    Energy Technology Data Exchange (ETDEWEB)

    Marcath, Matthew J., E-mail: mmarcath@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Shin, Tony H.; Clarke, Shaun D. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Peerani, Paolo [European Commission at the Joint Research Centre, Ispra (Italy); Pozzi, Sara A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States)

    2016-09-11

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a {sup 252}Cf, a 0.84 g {sup 240}Pu{sub eff} metal, and a 1.63 g {sup 240}Pu{sub eff} metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons. - Highlights: • Pu-240 prompt fission fast-neutron anisotropy was quantified for the first time. • MCNPX-PoliMi and MPPost codes were used to remove cross-talk neutron detections from experiment results. • Cf-252 spontaneous fission neutrons were found to be more anisotropic than Pu-240 neutrons.

  7. Neutron angular distribution in plutonium-240 spontaneous fission

    Science.gov (United States)

    Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.

    2016-09-01

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.

  8. An onboard star catalog for satellite angular attitude estimation

    Science.gov (United States)

    Kruzhilov, Ivan; Chernetsov, Andrey; Zakharov, Andrei; Kruzhilov, Svyatoslav

    2017-09-01

    Accuracy assessment of the satellite remote sensing depends on the angular attitude estimation precision. The 1 arc second error in attitude estimation causes 2.5-meter error in the accuracy derived from remote sensing data for the 500 km orbit. Different kind of momentum wheels, propulsions and sensors help correct spacecraft torque moment to stabilize it in the orbit. Star tracker is the most precise optical sensor for spacecraft angular attitude estimation. An onboard guide star catalog containing data for star pattern identification is essential for star tracker operating. The total number of stars, the faintest stellar magnitude, completeness and uniformity are the key specifications of a star catalog influencing many characteristic of a star tracker. The steps of creating guide star catalog are: instrumental stellar magnitude estimation with respect to the star tracker spectral response, clusterization of nearby stars, removing of unreliable stars and final star selection. An iterative algorithm for thinning down the catalog allows reducing appreciably the number of stars in the catalog and improving its uniformity. The key point of the algorithm is the lower bound evaluation of star number in the FOV (field of view) for every boresight position within a triangle area. The algorithm uses recursive quaternary division of the icosahedron for the celestial sphere tessellation. The correction methods of stellar aberration and star proper motion are discussed as well.

  9. Scale factor measure method without turntable for angular rate gyroscope

    Science.gov (United States)

    Qi, Fangyi; Han, Xuefei; Yao, Yanqing; Xiong, Yuting; Huang, Yuqiong; Wang, Hua

    2018-03-01

    In this paper, a scale factor test method without turntable is originally designed for the angular rate gyroscope. A test system which consists of test device, data acquisition circuit and data processing software based on Labview platform is designed. Taking advantage of gyroscope's sensitivity of angular rate, a gyroscope with known scale factor, serves as a standard gyroscope. The standard gyroscope is installed on the test device together with a measured gyroscope. By shaking the test device around its edge which is parallel to the input axis of gyroscope, the scale factor of the measured gyroscope can be obtained in real time by the data processing software. This test method is fast. It helps test system miniaturized, easy to carry or move. Measure quarts MEMS gyroscope's scale factor multi-times by this method, the difference is less than 0.2%. Compare with testing by turntable, the scale factor difference is less than 1%. The accuracy and repeatability of the test system seems good.

  10. Schematic memory components converge within angular gyrus during retrieval

    Science.gov (United States)

    Wagner, Isabella C; van Buuren, Mariët; Kroes, Marijn CW; Gutteling, Tjerk P; van der Linden, Marieke; Morris, Richard G; Fernández, Guillén

    2015-01-01

    Mental schemas form associative knowledge structures that can promote the encoding and consolidation of new and related information. Schemas are facilitated by a distributed system that stores components separately, presumably in the form of inter-connected neocortical representations. During retrieval, these components need to be recombined into one representation, but where exactly such recombination takes place is unclear. Thus, we asked where different schema components are neuronally represented and converge during retrieval. Subjects acquired and retrieved two well-controlled, rule-based schema structures during fMRI on consecutive days. Schema retrieval was associated with midline, medial-temporal, and parietal processing. We identified the multi-voxel representations of different schema components, which converged within the angular gyrus during retrieval. Critically, convergence only happened after 24-hour-consolidation and during a transfer test where schema material was applied to novel but related trials. Therefore, the angular gyrus appears to recombine consolidated schema components into one memory representation. DOI: http://dx.doi.org/10.7554/eLife.09668.001 PMID:26575291

  11. Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar

    Directory of Open Access Journals (Sweden)

    Xiaoli Zhou

    2015-01-01

    Full Text Available The two-dimensional angular resolution limit (ARL of elevation and azimuth for MIMO radar with ultrawideband (UWB noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach is based on the generalized likelihood ratio test (GLRT with given probabilities of false alarm and detection, while the estimation-theoretic approach is based on Smith’s criterion which involves the Cramér-Rao lower bound (CRLB. Furthermore, the relationship between the two approaches is presented, and the factors affecting the SARL, that is, detection parameters, transmit waveforms, array geometry, signal-to-noise ratio (SNR, and parameters of target (i.e., radar cross section (RCS and direction, are analyzed. Compared with the conventional radar resolution theory defined by the ambiguity function, the SARL reflects the practical resolution ability of radar and can provide an optimization criterion for radar system design.

  12. Network representations of angular regions for electromagnetic scattering.

    Directory of Open Access Journals (Sweden)

    Vito G Daniele

    Full Text Available Network modeling in electromagnetics is an effective technique in treating scattering problems by canonical and complex structures. Geometries constituted of angular regions (wedges together with planar layers can now be approached with the Generalized Wiener-Hopf Technique supported by network representation in spectral domain. Even if the network representations in spectral planes are of great importance by themselves, the aim of this paper is to present a theoretical base and a general procedure for the formulation of complex scattering problems using network representation for the Generalized Wiener Hopf Technique starting basically from the wave equation. In particular while the spectral network representations are relatively well known for planar layers, the network modelling for an angular region requires a new theory that will be developed in this paper. With this theory we complete the formulation of a network methodology whose effectiveness is demonstrated by the application to a complex scattering problem with practical solutions given in terms of GTD/UTD diffraction coefficients and total far fields for engineering applications. The methodology can be applied to other physics fields.

  13. The soil moisture velocity equation

    Science.gov (United States)

    Ogden, Fred L.; Allen, Myron B.; Lai, Wencong; Zhu, Jianting; Seo, Mookwon; Douglas, Craig C.; Talbot, Cary A.

    2017-06-01

    Numerical solution of the one-dimensional Richards' equation is the recommended method for coupling groundwater to the atmosphere through the vadose zone in hyperresolution Earth system models, but requires fine spatial discretization, is computationally expensive, and may not converge due to mathematical degeneracy or when sharp wetting fronts occur. We transformed the one-dimensional Richards' equation into a new equation that describes the velocity of moisture content values in an unsaturated soil under the actions of capillarity and gravity. We call this new equation the Soil Moisture Velocity Equation (SMVE). The SMVE consists of two terms: an advection-like term that accounts for gravity and the integrated capillary drive of the wetting front, and a diffusion-like term that describes the flux due to the shape of the wetting front capillarity profile divided by the vertical gradient of the capillary pressure head. The SMVE advection-like term can be converted to a relatively easy to solve ordinary differential equation (ODE) using the method of lines and solved using a finite moisture-content discretization. Comparing against analytical solutions of Richards' equation shows that the SMVE advection-like term is >99% accurate for calculating infiltration fluxes neglecting the diffusion-like term. The ODE solution of the SMVE advection-like term is accurate, computationally efficient and reliable for calculating one-dimensional vadose zone fluxes in Earth system and large-scale coupled models of land-atmosphere interaction. It is also well suited for use in inverse problems such as when repeat remote sensing observations are used to infer soil hydraulic properties or soil moisture.type="synopsis">type="main">Plain Language SummarySince its original publication in 1922, the so-called Richards' equation has been the only rigorous way to couple groundwater to the land surface through the unsaturated zone that lies between the water table and land surface. The soil

  14. Role of muscle pulleys in producing eye position-dependence in the angular vestibuloocular reflex: a model-based study

    Science.gov (United States)

    Thurtell, M. J.; Kunin, M.; Raphan, T.; Wall, C. C. (Principal Investigator)

    2000-01-01

    the roll gain of the angular vestibuloocular reflex was modified during the initial period of the response, while pulley coefficient was maintained at 0.5. Hence a roll gain modification allows stabilization of the retinal image without requiring a change in the pulley effect. Our results therefore indicate that the eye position-dependent velocity axis tilts could arise due to the effects of the pulleys and that a roll gain modification in the central vestibular structures may be responsible for countering the pulley effect.

  15. SDSS-IV MaNGA: Stellar angular momentum of about 2300 galaxies: unveiling the bimodality of massive galaxy properties

    Science.gov (United States)

    Graham, Mark T.; Cappellari, Michele; Li, Hongyu; Mao, Shude; Bershady, Matthew; Bizyaev, Dmitry; Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Law, David R.; Pan, Kaike; Thomas, Daniel; Wake, David A.; Weijmans, Anne-Marie; Westfall, Kyle B.; Yan, Renbin

    2018-03-01

    We measure λ _{R_e}, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, ɛ, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the MaNGA survey, the largest such sample to date. We use the (λ _{R_e}, ɛ ) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λ _{R_e} measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λ _{R_e}. Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λ _{R_e}, ɛ ) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λ _{R_e} and ɛ definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90○ in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above M ≥ 2 × 1011M⊙ where a significant number of high-mass fast rotators also exist.

  16. Rotational explanation of the high-velocity meolecular emission from the Orion Molecular Cloud

    International Nuclear Information System (INIS)

    Clark, F.O.; Biretta, J.A.; Martin, H.M.

    1979-01-01

    The high-velocity molecular emission of the Orion Molecular Cloud has been sampled using the J/sub N/=2 2 --1 1 rotational spectral line of the SO molecule. The resulting profile, including the high-velocity wings, has been reproduced using only known large-scale properties of the gas and applications of the results of published theoretical calculations. No new physical mechanism is required; observed rotation and conservation of angular momentum are sufficient to reproduce the line profile. The resulting physical state appears to be consistent with all known physical properties. This solution is not unique, but indicates the strengths and weaknesses of such a model for interpretation of Orion as well as the similarities of alternative explanations

  17. On the Angular Momentum Loss of Tropical Cyclones: An f-Plane Approximation

    Science.gov (United States)

    Kang, Hyun-Gyu; Cheong, Hyeong-Bin; Kim, Won-Ho

    2018-02-01

    The angular momentum for ideal axisymmetric tropical cyclones on the f-plane is investigated with a focus on the total-volume integrated quantity. Budget analysis of the momentum equation at cylindrical coordinates shows that a tropical cyclone loses angular momentum during its development and mature stages due to the dynamical difference between the viscous inward-flow near the surface and the angular momentum conserving outward-flow aloft. The total relative angular momentum of a tropical cyclone, as a result, can be negative (i.e., implying anticyclonic rotation as a whole) despite intense cyclonic wind in the tropospheric layers. This anticyclonic rotation was measured in terms of the super-rotation ratio, the ratio of total relative angular momentum to the planetary angular momentum. Simulations with the numerical model of Weather Research and Forecasting (WRF) version 3.4.1 was found to be in favor of the theoretical angular-momentum budget analysis. It was revealed in the numerical simulations that the super-rotation ratio was negative, indicating a sub-rotation, as was predicted by analysis. The sub-rotation ratio was found to be less than one percent for typical tropical cyclones. To show the angular momentum decrease even in the decaying stage, numerical simulations where the thermal forcing by sea surface temperature switched off in the mature stage were carried out. In support of the angular momentum budget analysis, the results indicated that the angular momentum also decreases for a while soon after the forcing was eliminated.

  18. On the angular momentum loss of tropical cyclones: An f-plane approximation

    Science.gov (United States)

    Kang, Hyun-Gyu; Cheong, Hyeong-Bin; Kim, Won-Ho

    2017-12-01

    The angular momentum for ideal axisymmetric tropical cyclones on the f-plane is investigated with a focus on the total-volume integrated quantity. Budget analysis of the momentum equation at cylindrical coordinates shows that a tropical cyclone loses angular momentum during its development and mature stages due to the dynamical difference between the viscous inward-flow near the surface and the angular momentum conserving outward-flow aloft. The total relative angular momentum of a tropical cyclone, as a result, can be negative (i.e., implying anticyclonic rotation as a whole) despite intense cyclonic wind in the tropospheric layers. This anticyclonic rotation was measured in terms of the super-rotation ratio, the ratio of total relative angular momentum to the planetary angular momentum. Simulations with the numerical model of Weather Research and Forecasting (WRF) version 3.4.1 was found to be in favor of the theoretical angular-momentum budget analysis. It was revealed in the numerical simulations that the super-rotation ratio was negative, indicating a sub-rotation, as was predicted by analysis. The sub-rotation ratio was found to be less than one percent for typical tropical cyclones. To show the angular momentum decrease even in the decaying stage, numerical simulations where the thermal forcing by sea surface temperature switched off in the mature stage were carried out. In support of the angular momentum budget analysis, the results indicated that the angular momentum also decreases for a while soon after the forcing was eliminated.

  19. CONNECTING ANGULAR MOMENTUM AND GALACTIC DYNAMICS: THE COMPLEX INTERPLAY BETWEEN SPIN, MASS, AND MORPHOLOGY

    International Nuclear Information System (INIS)

    Teklu, Adelheid F.; Remus, Rhea-Silvia; Dolag, Klaus; Beck, Alexander M.; Burkert, Andreas; Schulze, Felix; Steinborn, Lisa K.; Schmidt, Andreas S.

    2015-01-01

    The evolution and distribution of the angular momentum of dark matter (DM) halos have been discussed in several studies over the past decades. In particular, the idea arose that angular momentum conservation should allow us to infer the total angular momentum of the entire DM halo from measuring the angular momentum of the baryonic component, which is populating the center of the halo, especially for disk galaxies. To test this idea and to understand the connection between the angular momentum of the DM halo and its galaxy, we use a state-of-the-art, hydrodynamical cosmological simulation taken from the set of Magneticum Pathfinder simulations. Thanks to the inclusion of the relevant physical processes, the improved underlying numerical methods, and high spatial resolution, we successfully produce populations of spheroidal and disk galaxies self-consistently. Thus, we are able to study the dependence of galactic properties on their morphology. We find that (1) the specific angular momentum of stars in disk and spheroidal galaxies as a function of their stellar mass compares well with observational results; (2) the specific angular momentum of the stars in disk galaxies is slightly smaller compared to the specific angular momentum of the cold gas, in good agreement with observations; (3) simulations including the baryonic component show a dichotomy in the specific stellar angular momentum distribution when splitting the galaxies according to their morphological type (this dichotomy can also be seen in the spin parameter, where disk galaxies populate halos with slightly larger spin compared to spheroidal galaxies); (4) disk galaxies preferentially populate halos in which the angular momentum vector of the DM component in the central part shows a better alignment to the angular momentum vector of the entire halo; and (5) the specific angular momentum of the cold gas in disk galaxies is approximately 40% smaller than the specific angular momentum of the total DM halo

  20. High velocity impact experiment (HVIE)

    Energy Technology Data Exchange (ETDEWEB)

    Toor, A.; Donich, T.; Carter, P.

    1998-02-01

    The HVIE space project was conceived as a way to measure the absolute EOS for approximately 10 materials at pressures up to {approximately}30 Mb with order-of-magnitude higher accuracy than obtainable in any comparable experiment conducted on earth. The experiment configuration is such that each of the 10 materials interacts with all of the others thereby producing one-hundred independent, simultaneous EOS experiments The materials will be selected to provide critical information to weapons designers, National Ignition Facility target designers and planetary and geophysical scientists. In addition, HVIE will provide important scientific information to other communities, including the Ballistic Missile Defense Organization and the lethality and vulnerability community. The basic HVIE concept is to place two probes in counter rotating, highly elliptical orbits and collide them at high velocity (20 km/s) at 100 km altitude above the earth. The low altitude of the experiment will provide quick debris strip-out of orbit due to atmospheric drag. The preliminary conceptual evaluation of the HVIE has found no show stoppers. The design has been very easy to keep within the lift capabilities of commonly available rides to low earth orbit including the space shuttle. The cost of approximately 69 million dollars for 100 EOS experiment that will yield the much needed high accuracy, absolute measurement data is a bargain!

  1. Group Velocity for Leaky Waves

    Science.gov (United States)

    Rzeznik, Andrew; Chumakova, Lyubov; Rosales, Rodolfo

    2017-11-01

    In many linear dispersive/conservative wave problems one considers solutions in an infinite medium which is uniform everywhere except for a bounded region. In general, localized inhomogeneities of the medium cause partial internal reflection, and some waves leak out of the domain. Often one only desires the solution in the inhomogeneous region, with the exterior accounted for by radiation boundary conditions. Formulating such conditions requires definition of the direction of energy propagation for leaky waves in multiple dimensions. In uniform media such waves have the form exp (d . x + st) where d and s are complex and related by a dispersion relation. A complex s is required since these waves decay via radiation to infinity, even though the medium is conservative. We present a modified form of Whitham's Averaged Lagrangian Theory along with modulation theory to extend the classical idea of group velocity to leaky waves. This allows for solving on the bounded region by representing the waves as a linear combination of leaky modes, each exponentially decaying in time. This presentation is part of a joint project, and applications of these results to example GFD problems will be presented by L. Chumakova in the talk ``Leaky GFD Problems''. This work is partially supported by NSF Grants DMS-1614043, DMS-1719637, and 1122374, and by the Hertz Foundation.

  2. Geotail observations of FTE velocities

    Directory of Open Access Journals (Sweden)

    G. I. Korotova

    2009-01-01

    Full Text Available We discuss the plasma velocity signatures expected in association with flux transfer events (FTEs. Events moving faster than or opposite the ambient media should generate bipolar inward/outward (outward/inward flow perturbations normal to the nominal magnetopause in the magnetosphere (magnetosheath. Flow perturbations directly upstream and downstream from the events should be in the direction of event motion. Flows on the flanks should be in the direction opposite the motion of events moving at subsonic and subAlfvénic speeds relative to the ambient plasma. Events moving with the ambient flow should generate no flow perturbations in the ambient plasma. Alfvén waves propagating parallel (antiparallel to the axial magnetic field of FTEs may generate anticorrelated (correlated magnetic field and flow perturbations within the core region of FTEs. We present case studies illustrating many of these signatures. In the examples considered, Alfvén waves propagate along event axes away from the inferred reconnection site. A statistical study of FTEs observed by Geotail over a 3.5-year period reveals that FTEs within the magnetosphere invariably move faster than the ambient flow, while those in the magnetosheath move both faster and slower than the ambient flow.

  3. Reciprocally-Rotating Velocity Obstacles

    KAUST Repository

    Giese, Andrew

    2014-05-01

    © 2014 IEEE. Modern multi-agent systems frequently use highlevel planners to extract basic paths for agents, and then rely on local collision avoidance to ensure that the agents reach their destinations without colliding with one another or dynamic obstacles. One state-of-the-art local collision avoidance technique is Optimal Reciprocal Collision Avoidance (ORCA). Despite being fast and efficient for circular-shaped agents, ORCA may deadlock when polygonal shapes are used. To address this shortcoming, we introduce Reciprocally-Rotating Velocity Obstacles (RRVO). RRVO generalizes ORCA by introducing a notion of rotation for polygonally-shaped agents. This generalization permits more realistic motion than ORCA and does not suffer from as much deadlock. In this paper, we present the theory of RRVO and show empirically that it does not suffer from the deadlock issue ORCA has, permits agents to reach goals faster, and has a comparable collision rate at the cost of performance overhead quadratic in the (typically small) user-defined parameter δ.

  4. Computing discharge using the index velocity method

    Science.gov (United States)

    Levesque, Victor A.; Oberg, Kevin A.

    2012-01-01

    Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression

  5. The GALAH Survey: Stellar streams and how stellar velocity distributions vary with Galactic longitude, hemisphere and metallicity

    Science.gov (United States)

    Quillen, Alice C.; De Silva, Gayandhi; Sharma, Sanjib; Hayden, Michael; Freeman, Ken; Bland-Hawthorn, Joss; Žerjal, Maruša; Asplund, Martin; Buder, Sven; D'Orazi, Valentina; Duong, Ly; Kos, Janez; Lin, Jane; Lind, Karin; Martell, Sarah; Schlesinger, Katharine; Simpson, Jeffrey D.; Zucker, Daniel B.; Zwitter, Tomaz; Anguiano, Borja; Carollo, Daniela; Casagrande, Luca; Cotar, Klemen; Cottrell, Peter L.; Ireland, Michael; Kafle, Prajwal R.; Horner, Jonathan; Lewis, Geraint F.; Nataf, David M.; Ting, Yuan-Sen; Watson, Fred; Wittenmyer, Rob; Wyse, Rosemary

    2018-04-01

    Using GALAH survey data of nearby stars, we look at how structure in the planar (u, v) velocity distribution depends on metallicity and on viewing direction within the Galaxy. In nearby stars with distance d ≲ 1 kpc, the Hercules stream is most strongly seen in higher metallicity stars [Fe/H]>0.2. The Hercules stream peak v value depends on viewed galactic longitude, which we interpret as due to the gap between the stellar stream and more circular orbits being associated with a specific angular momentum value of about 1640 km s-1 kpc. The association of the gap with a particular angular momentum value supports a bar resonant model for the Hercules stream. Moving groups previously identified in Hipparcos observations are easiest to see in stars nearer than 250 pc, and their visibility and peak velocities in the velocity distributions depends on both viewing direction (galactic longitude and hemisphere) and metallicity. We infer that there is fine structure in local velocity distributions that varies over distances of a few hundred pc in the Galaxy.

  6. The JADE project: an angular cosmic ray detector

    Science.gov (United States)

    Le Maire, Victor; Jago, Alban; Mertens, Alexandre; de Crombrugghe, Guerric; Reydams, Marc; van Vynckt, Delphine; Denies, Jonathan; de Lobkowicz, Ysaline

    JADE (JUMP Angular Detection Experiment) is part of the JUMP Martian mission simulation conducted by students in the Mars Desert Research Station (MDRS) a habitat installed by the Mars Society (MS) in the Utah desert. The campaign was supported by ILEWG International Lunar Exploration Working Group, ESTEC, NASA Ames, and partners. It consists in a cosmic ray detector that can measure the angle of incidence of the particles. To develop such instru-ments, one usually uses two pixel silicium detectors that allow computing the particle trajectory. However such equipments are very expensive and require a complex electronic interface. This implies also that a significant amount of data has to be collected when a particle goes through the detector which can rapidly become a difficult constraint for limited bandwidth system as used in space instruments. JADE will be a modification an alternative solution proposed in [1], and it will take advantage of the geometry of the instrument in order to measure the incidence angle, with the innovative use of scintillators (a crystal emitting light when crossed by a charged particle) which are cheaper and stronger than silicium sensors. The detector consists in four scintillators disposed one above the other with a well determined relative angle (30). When a particle goes through a scintillator, light is emitted, collected through optical fibers and transformed into an electrical signal by a photomultiplier. This signal is proportional to the energy deposited in the scintillator by the particle which in turn is proportional to the distance travelled by the particle into the scintillator. Based on the distance travelled in each scintillator, it is then possible to compute the incidence angle. During the simulation several aspects of the use of this detector by astronauts will be tested. Its installation by astronauts wearing EVA suits will be studied with care. Furthermore, we will try to find an efficient way to fix the detector to

  7. A new unity for angular measurements in strabismus.

    Science.gov (United States)

    Bicas, Harley E A

    2014-10-01

    The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself ). The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%), but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller.) Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A mathematical

  8. A new unity for angular measurements in strabismus

    Directory of Open Access Journals (Sweden)

    Harley E. A. Bicas

    2014-10-01

    Full Text Available The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself . The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%, but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller. Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A

  9. On whistler-mode group velocity

    International Nuclear Information System (INIS)

    Sazhin, S.S.

    1986-01-01

    An analytical of the group velocity of whistler-mode waves propagating parallel to the magnetic field in a hot anisotropic plasma is presented. Some simple approximate formulae, which can be used for the magnetospheric applications, are derived. These formulae can predict some properties of this group velocity which were not previously recognized or were obtained by numerical methods. In particular, it is pointed out that the anisotropy tends to compensate for the influence of the electron temperature on the value of the group velocity when the wave frequency is well below the electron gyrofrequency. It is predicted, that under conditions at frequencies near the electron gyrofrequency, this velocity tends towards zero

  10. Demonstration of a Vector Velocity Technique

    DEFF Research Database (Denmark)

    Hansen, Peter Møller; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa......With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner...

  11. Velocity measurement of conductor using electromagnetic induction

    International Nuclear Information System (INIS)

    Kim, Gu Hwa; Kim, Ho Young; Park, Joon Po; Jeong, Hee Tae; Lee, Eui Wan

    2002-01-01

    A basic technology was investigated to measure the speed of conductor by non-contact electromagnetic method. The principle of the velocity sensor was electromagnetic induction. To design electromagnet for velocity sensor, 2D electromagnetic analysis was performed using FEM software. The sensor output was analyzed according to the parameters of velocity sensor, such as the type of magnetizing currents and the lift-off. Output of magnetic sensor was linearly depended on the conductor speed and magnetizing current. To compensate the lift-off changes during measurement of velocity, the other magnetic sensor was put at the pole of electromagnet.

  12. Angular Spacing Control for Segmented Data Pages in Angle-Multiplexed Holographic Memory

    Science.gov (United States)

    Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Kikuchi, Hiroshi; Shimidzu, Naoki; Ando, Toshio; Masaki, Kazuyoshi; Shimizu, Takehiro

    2011-09-01

    To improve the recording density of angle-multiplexed holographic memory, it is effective to increase the numerical aperture of the lens and to shorten the wavelength of the laser source as well as to increase the multiplexing number. The angular selectivity of a hologram, which determines the multiplexing number, is dependent on the incident angle of not only the reference beam but also the signal beam to the holographic recording medium. The actual signal beam, which is a convergent or divergent beam, is regarded as the sum of plane waves that have different propagation directions, angular selectivities, and optimal angular spacings. In this paper, focusing on the differences in the optimal angular spacing, we proposed a method to control the angular spacing for each segmented data page. We investigated the angular selectivity of a hologram and crosstalk for segmented data pages using numerical simulation. The experimental results showed a practical bit-error rate on the order of 10-3.

  13. Concentration dependence of inhomogeneous broadening in perturbed angular correlation spectroscopy

    Science.gov (United States)

    Moreno, Carlos; Hodges, Jeffery A.; Park, Tyler; Stufflebeam, Michael; Evenson, W.; Matheson, P.; Zacate, M. O.

    2008-10-01

    Since real crystals always include defects, the effect of the defects on crystal properties depends on how many defects are present, i.e. on defect concentration. In perturbed angular correlation (PAC), these defects produce damping of the correlation signal in time and broadening of the frequency spectrum. This ``inhomogeneous broadening'' depends quantitatively on defect concentration, so the size of the broadening in a PAC spectrum can be a measure of the concentration of defects. Using simulated PAC spectra and independent component analysis to obtain the probability distribution function for electric field gradient (EFG) components, we have found defect concentration-dependent parameters for the probability functions. This allows us to calculate broadened PAC spectra for any selected defect concentration. It also allows us to fit defect concentration from an experimental PAC spectrum. This work will be applied initially to broadened PAC data from β-Mn, Al-doped β-Mn, and Sr2RuO4.

  14. Angular correlation of annihilation photons in ice single crystals

    DEFF Research Database (Denmark)

    Mogensen, O. E.; Kvajic, G.; Eldrup, Morten Mostgaard

    1971-01-01

    -lattice vectors g⃗ on the direction perpendicular to the slits and the sample surface. The relative area of the central plus the side peaks was (15.2 ± 0.4)% for all curves. All the peaks are interpreted as due to parapositronium annihilation. The side peaks are explained as evidence for the positronium center......Linear-slit angular-correlation curves were obtained at - 148 °C for the [0001], [10¯10], and [11¯20] directions in single crystals of ice. Besides the narrow central peak, pronounced narrow side peaks were also observed. They occurred at angles θ=2πℏgz/mc, where gz is the projection of reciprocal...

  15. Marine algae are `taught' the basics of angular momentum

    Science.gov (United States)

    Allen, John Taylor

    2017-11-01

    Advanced modelling studies and high-resolution observations have shown that flows related to instability of the mesoscale ( 1-10 km scale) may provide both the fertilisation mechanism for nutrient-depleted (oligotrophic) surface waters and a subduction mechanism for the rapid export of phytoplankton biomass to the deep ocean. Here, a detailed multidisciplinary analysis of the data from an example high-resolution observational campaign is presented. The data provide direct observations of the transport of phytoplankton through baroclinic instability. Furthermore, the data confirm that this transport is constrained by the requirement to conserve angular momentum, expressed in a stratified water column as the conservation of potential vorticity. This constraint is clearly seen to produce long thin filaments of phytoplankton populations strained out along isopycnal vorticity annuli associated with mesoscale frontal instabilities.

  16. Investigation of an angular spectrum approach for pulsed ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2013-01-01

    An Angular Spectrum Approach (ASA)is formulated and employed to simulate linear pulsed ultra sound fields for high bandwidth signals. Ageometrically focused piston transducer is used as the acoustic source. Signals are cross-correlated to findthe true sound speed during the measurement to make...... the simulated and measured pulses in phase for comparisons. The calculated sound speed in the measurement is varied between 1487.45 m/s and 1487.75 m/s by using different initial values in the ASA simulation. Results from the pulsed ASA simulation susing both Field II simulated and hydrophone measured acoustic...... sources are compared to the Field II simulated and hydroph one measure dpulses, respectively. The total relative root mean squar e(RMS)errors of the pulsed ASA are investigated by using different time-point, zero-padding factors, spatial sampling interval and temporal sampling frequency in the sim ulation...

  17. Multiple orbital angular momentum generated by dielectric hybrid phase element

    Science.gov (United States)

    Wang, Xuewen; Kuchmizhak, Aleksandr; Hu, Dejiao; Li, Xiangping

    2017-09-01

    Vortex beam carrying multiple orbital angular momentum provides a new degree of freedom to manipulate light leading to the various exciting applications as trapping, quantum optics, information multiplexing, etc. Helical wavefront can be generated either via the geometric or the dynamic phase arising from a space-variant birefringence (q-plate) or from phase accumulation through propagation (spiral-phase-plate), respectively. Using fast direct laser writing technique we fabricate and characterize novel hybrid q-plate generating vortex beam simultaneously carrying two different high-order topological charges, which arise from the spin-orbital conversion and the azimuthal height variation of the recorded structures. We approve the versatile concept to generate multiple-OAM vortex beams combining the spin-orbital interaction and the phase accumulation in a single micro-scale device, a hybrid dielectric phase plate.

  18. Compact and high-resolution optical orbital angular momentum sorter

    Directory of Open Access Journals (Sweden)

    Chenhao Wan

    2017-03-01

    Full Text Available A compact and high-resolution optical orbital angular momentum (OAM sorter is proposed and demonstrated. The sorter comprises a quadratic fan-out mapper and a dual-phase corrector positioned in the pupil plane and the Fourier plane, respectively. The optical system is greatly simplified compared to previous demonstrations of OAM sorting, and the performance in resolution and efficiency is maintained. A folded configuration is set up using a single reflective spatial light modulator (SLM to demonstrate the validity of the scheme. The two phase elements are implemented on the left and right halves of the SLM and connected by a right-angle prism. Experimental results demonstrate the high resolution of the compact OAM sorter, and the current limit in efficiency can be overcome by replacing with transmissive SLMs and removing the beam splitters. This novel scheme paves the way for the miniaturization and integration of high-resolution OAM sorters.

  19. The High Angular Resolution Multiplicity of Massive Stars

    Science.gov (United States)

    2009-02-01

    because of the very short timescale of formation. Instead, the initial angular momentum of the natal cloud may end up (through a variety of processes...0.132 1.2 1 3 03272+0944 HDS 433 HD 21364 2005.8616 53.8 0.224 3.8 2 −6.9 −0.012 Romero (2007) 03284+6015 A 980 AB HD 21203 2007.6022 337.9 0.364 1.6... Romero , F. M. R. 2006a, IAU Comm. 26 Inf. Circ., 158 Romero , F. M. R. 2006b, IAU Comm. 26 Inf. Circ., 160 Romero , F. M. R. 2006c, IAU Comm. 26 Inf

  20. Integrated spectral study of small angular diameter galactic open clusters

    Science.gov (United States)

    Clariá, J. J.; Ahumada, A. V.; Bica, E.; Pavani, D. B.; Parisi, M. C.

    2017-10-01

    This paper presents flux-calibrated integrated spectra obtained at Complejo Astronómico El Leoncito (CASLEO, Argentina) for a sample of 9 Galactic open clusters of small angular diameter. The spectra cover the optical range (3800-6800 Å), with a resolution of ˜14 Å. With one exception (Ruprecht 158), the selected clusters are projected into the fourth Galactic quadrant (282o evaluate their membership status. The current cluster sample complements that of 46 open clusters previously studied by our group in an effort to gather a spectral library with several clusters per age bin. The cluster spectral library that we have been building is an important tool to tie studies of resolved and unresolved stellar content.