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

2015-09-18

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.

Analyzing angular distributions for two-step dissociation mechanisms in velocity map imaging.

Science.gov (United States)

Straus, Daniel B; Butler, Lynne M; Alligood, Bridget W; Butler, Laurie J

2013-08-15

Increasingly, velocity map imaging is becoming the method of choice to study photoinduced molecular dissociation processes. This paper introduces an algorithm to analyze the measured net speed, P(vnet), and angular, β(vnet), distributions of the products from a two-step dissociation mechanism, where the first step but not the second is induced by absorption of linearly polarized laser light. Typically, this might be the photodissociation of a C-X bond (X = halogen or other atom) to produce an atom and a momentum-matched radical that has enough internal energy to subsequently dissociate (without the absorption of an additional photon). It is this second step, the dissociation of the unstable radicals, that one wishes to study, but the measured net velocity of the final products is the vector sum of the velocity imparted to the radical in the primary photodissociation (which is determined by taking data on the momentum-matched atomic cophotofragment) and the additional velocity vector imparted in the subsequent dissociation of the unstable radical. The algorithm allows one to determine, from the forward-convolution fitting of the net velocity distribution, the distribution of velocity vectors imparted in the second step of the mechanism. One can thus deduce the secondary velocity distribution, characterized by a speed distribution P(v1,2°) and an angular distribution I(θ2°), where θ2° is the angle between the dissociating radical's velocity vector and the additional velocity vector imparted to the product detected from the subsequent dissociation of the radical.

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

Determination of angular rotation velocity of Dar'e wind turbine with straight blades

International Nuclear Information System (INIS)

Ershina, A.K.; Ershin, Sh.A.; Upnanov, T.K.

1999-01-01

In the report the method of angular velocity determination for wind turbine of given capacity with allowing for an average seasonal wind velocity and all geometrical and dynamical characteristics of the unit is presented. It is noted, that this wind turbine has following advantages: wind direction does not plays role due to vertical axis position of the turbine; electric generator and other equipment are arranged on the ground, that reduce construction's weight, expedite of servicing and repair; the wind turbine has high coefficient of wind energy use (ξ max =0.45)

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.))

Angular velocity and centripetal acceleration relationship

Science.gov (United States)

Monteiro, Martín; Cabeza, Cecilia; Marti, Arturo C.; Vogt, Patrik; Kuhn, Jochen

2014-05-01

During the last few years, the growing boom of smartphones has given rise to a considerable number of applications exploiting the functionality of the sensors incorporated in these devices. A sector that has unexpectedly taken advantage of the power of these tools is physics teaching, as reflected in several recent papers. In effect, the use of smartphones has been proposed in several physics experiments spanning mechanics, electromagnetism, optics, oscillations, and waves, among other subjects. Although mechanical experiments have received considerable attention, most of them are based on the use of the accelerometer. An aspect that has received less attention is the use of rotation sensors or gyroscopes. An additional advance in the use of these devices is given by the possibility of obtaining data using the accelerometer and the gyroscope simultaneously. The aim of this paper is to consider the relation between the centripetal acceleration and the angular velocity. Instead of using a formal laboratory setup, in this experiment a smartphone is attached to the floor of a merry-go-round, found in many playgrounds. Several experiments were performed with the roundabout rotating in both directions and with the smart-phone at different distances from the center. The coherence of the measurements is shown.

Isokinetic hamstrings-to-quadriceps peak torque ratio: the influence of sport modality, gender, and angular velocity.

Science.gov (United States)

Andrade, Marilia Dos Santos; De Lira, Claudio Andre Barbosa; Koffes, Fabiana De Carvalho; Mascarin, Naryana Cristina; Benedito-Silva, Ana Amélia; Da Silva, Antonio Carlos

2012-01-01

The purpose of this study was to determine differences in hamstrings-to-quadriceps (H/Q) peak torque ratios evaluated at different angular velocities between men and women who participate in judo, handball or soccer. A total of 166 athletes, including 58 judokas (26 females and 32 males), 39 handball players (22 females and 17 males), and 69 soccer players (17 females and 52 males), were evaluated using an isokinetic dynamometer. The H/Q isokinetic peak torque ratios were calculated at angular velocities of 1.05 rad · s⁻¹ and 5.23 rad · s⁻¹. In the analysis by gender, female soccer players produced lower H/Q peak torque ratios at 1.05 rad · s⁻¹ than males involved in the same sport. However, when H/Q peak torque ratio was assessed at 5.23 rad · s⁻¹, there were no significant differences between the sexes. In the analysis by sport, there were no differences among females at 1.05 rad · s⁻¹. In contrast, male soccer players had significantly higher H/Q peak torque ratios than judokas (66 ± 12% vs. 57 ± 14%, respectively). Female handball players produced significantly lower peak torque ratios at 5.23 rad · s⁻¹ than judokas or soccer players, whereas males presented no ratio differences among sports At 5.23 rad · s⁻¹. In the analysis by velocity, women's muscular ratios assessed at 1.05 rad · s⁻¹ were significantly lower than at 5.23 rad · s⁻¹ for all sports; among men, only judokas presented lower ratios at 1.05 rad · s⁻¹ than at 5.23 rad · s⁻¹. The present results suggest that sport modality and angular velocity influence the isokinetic strength profiles of men and women.

Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

Science.gov (United States)

Lin, Jun; Pakhomov, Andrew V.

2005-04-01

This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (˜ 3×10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ˜35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements.

Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

International Nuclear Information System (INIS)

Lin Jun; Pakhomov, Andrew V.

2005-01-01

This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (∼ 3x10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ∼35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements

Effects of Adaptation on Discrimination of Whisker Deflection Velocity and Angular Direction in a Model of the Barrel Cortex

Directory of Open Access Journals (Sweden)

Mainak J. Patel

2018-06-01

Full Text Available Two important stimulus features represented within the rodent barrel cortex are velocity and angular direction of whisker deflection. Each cortical barrel receives information from thalamocortical (TC cells that relay information from a single whisker, and TC input is decoded by barrel regular-spiking (RS cells through a feedforward inhibitory architecture (with inhibition delivered by cortical fast-spiking or FS cells. TC cells encode deflection velocity through population synchrony, while deflection direction is encoded through the distribution of spike counts across the TC population. Barrel RS cells encode both deflection direction and velocity with spike rate, and are divided into functional domains by direction preference. Following repetitive whisker stimulation, system adaptation causes a weakening of synaptic inputs to RS cells and diminishes RS cell spike responses, though evidence suggests that stimulus discrimination may improve following adaptation. In this work, I construct a model of the TC, FS, and RS cells comprising a single barrel system—the model incorporates realistic synaptic connectivity and dynamics and simulates both angular direction (through the spatial pattern of TC activation and velocity (through synchrony of the TC population spikes of a deflection of the primary whisker, and I use the model to examine direction and velocity selectivity of barrel RS cells before and after adaptation. I find that velocity and direction selectivity of individual RS cells (measured over multiple trials sharpens following adaptation, but stimulus discrimination using a simple linear classifier by the RS population response during a single trial (a more biologically meaningful measure than single cell discrimination over multiple trials exhibits strikingly different behavior—velocity discrimination is similar both before and after adaptation, while direction classification improves substantially following adaptation. This is the

Multiple Model Adaptive Attitude Control of LEO Satellite with Angular Velocity Constraints

Science.gov (United States)

Shahrooei, Abolfazl; Kazemi, Mohammad Hosein

2018-04-01

In this paper, the multiple model adaptive control is utilized to improve the transient response of attitude control system for a rigid spacecraft. An adaptive output feedback control law is proposed for attitude control under angular velocity constraints and its almost global asymptotic stability is proved. The multiple model adaptive control approach is employed to counteract large uncertainty in parameter space of the inertia matrix. The nonlinear dynamics of a low earth orbit satellite is simulated and the proposed control algorithm is implemented. The reported results show the effectiveness of the suggested scheme.

Fatigue influences lower extremity angular velocities during a single-leg drop vertical jump

OpenAIRE

Tamura, Akihiro; Akasaka, Kiyokazu; Otsudo, Takahiro; Shiozawa, Junya; Toda, Yuka; Yamada, Kaori

2017-01-01

[Purpose] Fatigue alters lower extremity landing strategies and decreases the ability to attenuate impact during landing. The purpose of this study was to reveal the influence of fatigue on dynamic alignment and joint angular velocities in the lower extremities during a single leg landing. [Subjects and Methods] The 34 female college students were randomly assigned to either the fatigue or control group. The fatigue group performed single-leg drop vertical jumps before, and after, the fatigue...

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.

Angular beam width of a slit-diffracted wave with noncollinear group and phase velocities

International Nuclear Information System (INIS)

Lock, Edwin H

2012-01-01

Taking magnetostatic surface wave diffraction as an example, this paper theoretically investigates the 2D diffraction pattern arising in the far-field region of a ferrite slab in the case of a plane wave with noncollinear group and phase velocities incident on a wide, arbitrarily oriented slit in an opaque screen. A universal analytical formula for the angular width of a diffracted beam is derived, which is valid for magnetostatic and other types of waves in anisotropic media and structures (including metamaterials) in 2D geometries. It is shown that the angular width of a diffracted beam in an anisotropic medium can not only take values greater or less than λ 0 /D (where λ 0 is the incident wavelength, and D is the slit width), but can also be zero under certain conditions. (methodological notes)

The effect of angular velocity and cycle on the dissipative properties of the knee during passive cyclic stretching: a matter of viscosity or solid friction.

Science.gov (United States)

Nordez, A; McNair, P J; Casari, P; Cornu, C

2009-01-01

The mechanisms behind changes in mechanical parameters following stretching are not understood clearly. This study assessed the effects of joint angular velocity on the immediate changes in passive musculo-articular properties induced by cyclic stretching allowing an appreciation of viscosity and friction, and their contribution to changes in torque that occur. Ten healthy subjects performed five passive knee extension/flexion cycles on a Biodex dynamometer at five preset angular velocities (5-120 deg/s). The passive torque and knee angle were measured, and the potential elastic energy stored during the loading and the dissipation coefficient were calculated. As the stretching velocity increased, so did stored elastic energy and the dissipation coefficient. The slope of the linear relationship between the dissipation coefficient and the angular velocity was unchanged across repetitions indicating that viscosity was unlikely to be affected. A difference in the y-intercept across repetitions 1 and 5 was indicative of a change in processes associated with solid friction. Electromyographical responses to stretching were low across all joint angular velocities. Torque changes during cyclic motion may primarily involve solid friction which is more indicative of rearrangement/slipping of collagen fibers rather than the redistribution of fluid and its constituents within the muscle. The findings also suggest that it is better to stretch slowly initially to reduce the amount of energy absorption required by tissues, but thereafter higher stretching speeds can be undertaken.

Vibration-dependent angular anisotropy in the photodetachment of O{sub 2}{sup -}, viewed with velocity-map imaging

Energy Technology Data Exchange (ETDEWEB)

Gibson, S T; Cavanagh, S J; Lewis, B R [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Gascooke, J R [School of Chemistry, Physics and Earth Sciences, Flinders University, SA 5001 (Australia); Mabbs, R [Department of Chemistry, Washington University, St Louis MO 63930-4899 (United States); Sanov, A, E-mail: Stephen.Gibson@anu.edu.a, E-mail: Steven.Cavanagh@anu.edu.a [Department of Chemistry, University of Arizona, Tucson AZ 85721-0041 (United States)

2009-11-01

The photodetachment spectrum of O{sub 2}{sup -} has been measured at a number of wavelengths using velocity-map imaging. The electron kinetic-energy resolution (< 5 meV) is sufficient to resolve the anion fine-structure splitting, vibrational and electronic structure. The electron angular distribution varies with the electron kinetic-energy, with a different behaviour for each vibronic band.

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.)

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 =…

Global Plate Velocities from the Global Positioning System

Science.gov (United States)

Larson, Kristine M.; Freymueller, Jeffrey T.; Philipsen, Steven

1997-01-01

We have analyzed 204 days of Global Positioning System (GPS) data from the global GPS network spanning January 1991 through March 1996. On the basis of these GPS coordinate solutions, we have estimated velocities for 38 sites, mostly located on the interiors of the Africa, Antarctica, Australia, Eurasia, Nazca, North America, Pacific, and South America plates. The uncertainties of the horizontal velocity components range from 1.2 to 5.0 mm/yr. With the exception of sites on the Pacific and Nazca plates, the GPS velocities agree with absolute plate model predictions within 95% confidence. For most of the sites in North America, Antarctica, and Eurasia, the agreement is better than 2 mm/yr. We find no persuasive evidence for significant vertical motions (less than 3 standard deviations), except at four sites. Three of these four were sites constrained to geodetic reference frame velocities. The GPS velocities were then used to estimate angular velocities for eight tectonic plates. Absolute angular velocities derived from the GPS data agree with the no net rotation (NNR) NUVEL-1A model within 95% confidence except for the Pacific plate. Our pole of rotation for the Pacific plate lies 11.5 deg west of the NNR NUVEL-1A pole, with an angular speed 10% faster. Our relative angular velocities agree with NUVEL-1A except for some involving the Pacific plate. While our Pacific-North America angular velocity differs significantly from NUVEL-1A, our model and NUVEL-1A predict very small differences in relative motion along the Pacific-North America plate boundary itself. Our Pacific-Australia and Pacific- Eurasia angular velocities are significantly faster than NUVEL-1A, predicting more rapid convergence at these two plate boundaries. Along the East Pacific Pise, our Pacific-Nazca angular velocity agrees in both rate and azimuth with NUVFL-1A.

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.

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 < 0.01). None of the observed racquet kinematics significantly correlated to the measures of forehand accuracy. These results confirmed mechanical logic and indicate that increased ball TAV is associated with a more closed racquet head impact angle (ranging from

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

Directory of Open Access Journals (Sweden)

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

2017-12-01

Full Text Available 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 < 0.01. None of the observed racquet kinematics significantly correlated to the measures of forehand accuracy. These results confirmed mechanical logic and indicate that increased ball TAV is associated with a more closed racquet head impact angle (ranging

Eilenberger equation for rotating superfluid 3He and calculation of the upper critical angular velocity Ω/sub c/2

International Nuclear Information System (INIS)

Schopohl, N.

1980-01-01

On the basis of Gorkov's formulation of superconductivity theory, generalized Eilenberger equations are derived which apply to rotating superfluid 3 He in the presence of a magnetic field h and finite superflow v. In analyogy to conventional type II superconductors, the possibility of vortex solutions in discussed. An implicit equation determining the upper critical angular velocity Ω/sub c/2 as a function of temperature T, magnetic field h, and superflow v parallel to the rotation axis is-inferred from the linearized Eilenberger equations. In contrast to the case of slowly rotating 3 He-A, the solution of the eigenvalue problem determining the order parameter Δ near the the upper critical angular velocity admits no coreless vortex no coreless solutions. The space-dependent amplitude of the order parameter is analogous to Abrikosov's vortex array solution, while the spin-orbit part is given either by a polar-state type or an Anderson-Brinkman-Morel (ABM)-state-type eigensolution. Among the possible eigensolutions the polar-state type yields for vanishing superflow v the highest critical rotation frequency. For finite superflow v parallel to the rotation axis, however, the ABM-state-type solution is stabilized in comparison to the polar state for Vertical BarvVertical Bar> or approx. =0.2π(Tc/sub c/0/T/sub F/)v/sub f/ at zero temperature

Time variations of the angular momentum of the sun

International Nuclear Information System (INIS)

Schatten, K.H.

1977-01-01

Time variations of density models of the Sun are investigated. This is an attempt to estimate the changing moment of inertia of the Sun in order to calculate the internal solar angular velocity based upon Newton's equation of motion. Previous estimates of dI/dt disagree with those based upon central densities in a homologously contracting model. It is shown that the homologously contracting model leads to large errors in dI/dt. Based upon an integration of Sears's solar model, dI/dt=-5.5 x 10 34 gm cm 2 s -1 . This suggests a core angular velocity of /sub thetar-italic/ = (0.15 +- 0.03) x 10 -3 s -1 , corresponding to a period of 0.5 +- 0.1 days, assuming a constant angular velocity with time. The brackets indicate a weighting which is discussed

EVOLUTION OF ROTATIONAL VELOCITIES OF A-TYPE STARS

International Nuclear Information System (INIS)

Yang Wuming; Bi Shaolan; Tian Zhijia; Meng Xiangcun

2013-01-01

The equatorial velocity of A-type stars undergoes an acceleration in the first third of the main sequence (MS) stage, but the velocity decreases as if the stars were not undergoing any redistribution of angular momentum in the external layers in the last stage of the MS phase. Our calculations show that the acceleration and the decrease of the equatorial velocity can be reproduced by the evolution of the differential rotation zero-age MS model with the angular momentum transport caused by hydrodynamic instabilities during the MS stage. The acceleration results from the fact that the angular momentum stored in the interiors of the stars is transported outward. In the last stage, the core and the radiative envelope are uncoupling, and the rotation of the envelope is a quasi-solid rotation; the uncoupling and the expansion of the envelope indicate that the decrease of the equatorial velocity approximately follows the slope for the change in the equatorial velocity of the model without any redistribution of angular momentum. When the fractional age 0.3 ∼ MS ∼< 0.5, the equatorial velocity remains almost constant for stars whose central density increases with age in the early stage of the MS phase, while the velocity decreases with age for stars whose central density decreases with age in the early stage of the MS phase.

Rotational speedups accompanying angular deceleration of a superfluid

International Nuclear Information System (INIS)

Campbell, L.J.

1979-01-01

Exact calculations of the angular deceleration of superfluid vortex arrays show momentary speedups in the angular velocity caused by coherent, multiple vortex loss at the boundary. The existence and shape of the speedups depend on the vortex friction, the deceleration rate, and the pattern symmetry. The phenomenon resembles, in several ways, that observed in pulsars

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.

Massive star formation by accretion. II. Rotation: how to circumvent the angular momentum barrier?

Science.gov (United States)

Haemmerlé, L.; Eggenberger, P.; Meynet, G.; Maeder, A.; Charbonnel, C.; Klessen, R. S.

2017-06-01

Context. Rotation plays a key role in the star-formation process, from pre-stellar cores to pre-main-sequence (PMS) objects. Understanding the formation of massive stars requires taking into account the accretion of angular momentum during their PMS phase. Aims: We study the PMS evolution of objects destined to become massive stars by accretion, focusing on the links between the physical conditions of the environment and the rotational properties of young stars. In particular, we look at the physical conditions that allow the production of massive stars by accretion. Methods: We present PMS models computed with a new version of the Geneva Stellar Evolution code self-consistently including accretion and rotation according to various accretion scenarios for mass and angular momentum. We describe the internal distribution of angular momentum in PMS stars accreting at high rates and we show how the various physical conditions impact their internal structures, evolutionary tracks, and rotation velocities during the PMS and the early main sequence. Results: We find that the smooth angular momentum accretion considered in previous studies leads to an angular momentum barrier and does not allow the formation of massive stars by accretion. A braking mechanism is needed in order to circumvent this angular momentum barrier. This mechanism has to be efficient enough to remove more than two thirds of the angular momentum from the inner accretion disc. Due to the weak efficiency of angular momentum transport by shear instability and meridional circulation during the accretion phase, the internal rotation profiles of accreting stars reflect essentially the angular momentum accretion history. As a consequence, careful choice of the angular momentum accretion history allows circumvention of any limitation in mass and velocity, and production of stars of any mass and velocity compatible with structure equations.

Measurement crankshaft angular speed of an OM403 engine

Directory of Open Access Journals (Sweden)

Biočanin Stojko

2017-01-01

Full Text Available In this paper, the methodology of the measurement of the angular speed of the crankshaft of a ten-cylinder diesel OM403 engine is presented, with regular and irregular engine operation. The angular velocity was measured under laboratory conditions, on already installed measuring equipment from the laboratory and on the break of a well known brand-Schenck, by using an optoelectronic incremental rotary encoder, a data acquisition module and the LabVIEW software for synchronization and management of the measuring equipment. The goal of this paper is to give a practical contribution to researches of measuring of crankshaft angular speed of the crankshaft engine OM 403.

Intracycle angular velocity control of cross-flow turbines

Science.gov (United States)

Strom, Benjamin; Brunton, Steven L.; Polagye, Brian

2017-08-01

Cross-flow turbines, also known as vertical-axis turbines, are attractive for power generation from wind and water currents. Some cross-flow turbine designs optimize unsteady fluid forces and maximize power output by controlling blade kinematics within one rotation. One established method is to dynamically pitch the blades. Here we introduce a mechanically simpler alternative: optimize the turbine rotation rate as a function of angular blade position. We demonstrate experimentally that this approach results in a 59% increase in power output over standard control methods. Analysis of fluid forcing and blade kinematics suggest that power increase is achieved through modification of the local flow conditions and alignment of fluid force and rotation rate extrema. The result is a low-speed, structurally robust turbine that achieves high efficiency and could enable a new generation of environmentally benign turbines for renewable power generation.

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.

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.)

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

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.

Helicity and evanescent waves. [Energy transport velocity, helicity, Lorentz transformation

Energy Technology Data Exchange (ETDEWEB)

Agudin, J L; Platzeck, A M [La Plata Univ. Nacional (Argentina); Albano, J R [Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina

1978-02-20

It is shown that the projection of the angular momentum of a circularly polarized electromagnetic evanescent wave along the mean velocity of energy transport (=helicity) can be reverted by a Lorentz transformation, in spite of the fact that this velocity is c.

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.…

Angular momentum transport and dynamo action in the sun - Implications of recent oscillation measurements

International Nuclear Information System (INIS)

Gilman, P. A.; Morrow, C. A.; Deluca, E. E.

1989-01-01

The implications of a newly proposed picture of the sun's internal rotation (Brown et al., 1989; Morrow, 1988) for the distribution and transport of angular momentum and for the solar dynamo are considered. The new results, derived from an analysis of solar acoustic oscillations, affect understanding of how momentum is cycled in the sun and provide clues as to how and where the solar dynamo is driven. The data imply that the only significant radial gradient of angular velocity exists in a transitional region between the bottom of the convection zone, which is rotating like the solar surface, and the top of the deep interior, which is rotating rigidly at a rate intermediate between the equatorial and polar rates at the surface. Thus the radial gradient must change sign at the latitude where the angular velocity of the surface matches that of the interior. These inferences suggest that the cycle of angular momentum that produces the observed latitudinal differential rotation in the convection zone may be coupled to layers of the interior beneath the convection zone. 35 refs

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

Gravitational Field of Ultrarelativistic Objects with Angular Momentum

Energy Technology Data Exchange (ETDEWEB)

Fursaev, Dmitri V [Dubna International University and Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141 980, Dubna, Moscow Region (Russian Federation)

2006-03-01

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.

THE ANGULAR MOMENTUM OF MAGNETIZED MOLECULAR CLOUD CORES: A TWO-DIMENSIONAL-THREE-DIMENSIONAL COMPARISON

International Nuclear Information System (INIS)

Dib, Sami; Csengeri, Timea; Audit, Edouard; Hennebelle, Patrick; Pineda, Jaime E.; Goodman, Alyssa A.; Bontemps, Sylvain

2010-01-01

In this work, we present a detailed study of the rotational properties of magnetized and self-gravitating dense molecular cloud (MC) cores formed in a set of two very high resolution three-dimensional (3D) MC simulations with decaying turbulence. The simulations have been performed using the adaptative mesh refinement code RAMSES with an effective resolution of 4096 3 grid cells. One simulation represents a mildly magnetically supercritical cloud and the other a strongly magnetically supercritical cloud. We identify dense cores at a number of selected epochs in the simulations at two density thresholds which roughly mimic the excitation densities of the NH 3 (J - K) = (1,1) transition and the N 2 H + (1-0) emission line. A noticeable global difference between the two simulations is the core formation efficiency (CFE) of the high-density cores. In the strongly supercritical simulations, the CFE is 33% per unit free-fall time of the cloud (t ff,cl ), whereas in the mildly supercritical simulations this value goes down to ∼6 per unit t ff,cl . A comparison of the intrinsic specific angular momentum (j 3D ) distributions of the cores with the specific angular momentum derived using synthetic two-dimensional (2D) velocity maps of the cores (j 2D ) shows that the synthetic observations tend to overestimate the true value of the specific angular momentum by a factor of ∼8-10. We find that the distribution of the ratio j 3D /j 2D of the cores peaks at around ∼0.1. The origin of this discrepancy lies in the fact that contrary to the intrinsic determination of j which sums up the individual gas parcels' contributions to the angular momentum, the determination of the specific angular momentum using the standard observational procedure which is based on a measurement on the global velocity gradient under the hypothesis of uniform rotation smoothes out the complex fluctuations present in the 3D velocity field. Our results may well provide a natural explanation for the

Stellar Angular Momentum Distributions and Preferential Radial Migration

Science.gov (United States)

Wyse, Rosemary; Daniel, Kathryne J.

2018-04-01

I will present some results from our recent investigations into the efficiency of radial migration in stellar disks of differing angular momentum distributions, within a given adopted 2D spiral disk potential. We apply to our models an analytic criterion that determines whether or not individual stars are in orbits that could lead to radial migration around the corotation resonance. We couch our results in terms of the local stellar velocity dispersion and find that the fraction of stars that could migrate radially decreases as the velocity dispersion increases. I will discuss implications and comparisons with the results of other approaches.

Asymmetric Velocity Distributions from Halo Density Profiles in the Eddington Approach

International Nuclear Information System (INIS)

Vergados, J. D.

2015-01-01

We show how to obtain the energy distribution f(E) in our vicinity starting from WIMP density profiles in a self-consistent way by employing the Eddington approach and adding reasonable angular momentum dependent terms in the expression of the energy. We then show how we can obtain the velocity dispersions and the asymmetry parameter β in terms of the parameters describing the angular momentum dependence. From this expression, for f(E), we proceed to construct an axially symmetric WIMP a velocity distribution, which, for a gravitationally bound system, automatically has a velocity upper bound and is characterized by the same asymmetriy β. This approach is tested and clarified by constructing analytic expressions in a simple model, with adequate structure. We then show how such velocity distributions can be used in determining the event rates, including modulation, in both the standard and the directional WIMP searches.

On the spherical harmonic expansion of the neutron angular distribution function

Energy Technology Data Exchange (ETDEWEB)

Depken, Sven

1959-03-15

The neutron (one-velocity) angular distribution function is expanded in terms of spherical harmonic tensors. The solution to the equations of the moments is given explicitly and the result is applied to the plane, spherical and cylinder symmetrical cases.

On the spherical harmonic expansion of the neutron angular distribution function

International Nuclear Information System (INIS)

Depken, Sven

1959-03-01

The neutron (one-velocity) angular distribution function is expanded in terms of spherical harmonic tensors. The solution to the equations of the moments is given explicitly and the result is applied to the plane, spherical and cylinder symmetrical cases

EVIDENCE FOR INFALLING GAS OF LOW ANGULAR MOMENTUM TOWARD THE L1551 NE KEPLERIAN CIRCUMBINARY DISK

Energy Technology Data Exchange (ETDEWEB)

Takakuwa, Shigehisa [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Saito, Masao [Joint ALMA Observatory, Ave. Alonso de Cordova 3107, Vitacura, Santiago (Chile); Lim, Jeremy [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Saigo, Kazuya, E-mail: takakuwa@asiaa.sinica.edu.tw [ALMA Project Office, National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)

2013-10-10

We report follow-up C{sup 18}O(3-2) line observations of the Class I binary protostellar system L1551 NE with the Submillimeter Array in its compact and subcompact configurations. Our previous observations at a higher angular resolution in the extended configuration revealed a circumbinary disk exhibiting Keplerian motion. The combined data, with more extensive spatial coverage (∼140-2000 AU), verify the presence of a Keplerian circumbinary disk and reveal for the first time a distinct low-velocity (∼< ± 0.5 km s{sup –1} from the systemic velocity) component that displays a velocity gradient along the minor axis of the circumbinary disk. Our simple model that reproduces the main features seen in the position-velocity diagrams comprises a circumbinary disk exhibiting Keplerian motion out to a radius of ∼300 AU, beyond which the gas exhibits pure infall at a constant velocity of ∼0.6 km s{sup –1}. This velocity is significantly smaller than the expected free-fall velocity of ∼2.2 km s{sup –1} onto the L1551 NE protostellar mass of ∼0.8 M{sub ☉} at ∼300 AU, suggesting that the infalling gas is decelerated as it moves into regions of high gas pressure in the circumbinary disk. The discontinuity in angular momenta between the outer infalling gas and the inner Keplerian circumbinary disk implies an abrupt transition in the effectiveness at which magnetic braking is able to transfer angular momentum outward, a result perhaps of the different plasma β values and the ionization fractions between the outer and inner regions of the circumbinary disk.

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)].

Momentum and Angular Momentum Transfer in Oblique Impacts: Implications for Asteroid Rotations

Science.gov (United States)

Yanagisawa, Masahisa; Hasegawa, Sunao; Shirogane, Nobutoshi

1996-09-01

We conducted a series of high velocity oblique impact experiments (0.66-6.7 km/s) using polycarbonate (plastic) projectiles and targets made of mortar, aluminum alloy, and mild steel. We then calculated the efficiencies of momentum transfer for small cratering impacts. They are η = (M‧Vn‧)/(mvn) and ζ = (M‧Vt‧)/(mvt), wheremandvare the mass and velocity of a projectile, andM‧ andV‧ represent those of a postimpact target. Subscripts “n” and “t” denote the components normal and tangential to the target surface at the impact point, respectively. The main findings are: (1) η increases with increasing impact velocity; (2) η is larger for mortar than for ductile metallic targets; (3) ζ for mortar targets seems to increase with the impact velocity in the velocity range less than about 2 km/s and decrease with it in the higher velocity range; (4) ζ for the aluminum alloy targets correlates negatively with incident zenith angle of the projectile. In addition to these findings on the momentum transfer, we show theoretically that “ζL” can be expressed by η and ζ for small cratering impact. Here, ζLis the spin angular momentum that the target acquires at impact divided by the collisional angular momentum due to the projectile. This is an important parameter to study the collisional evolution of asteroid rotation. For a spherical target, ζLis shown to be well approximated by ζ.

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

Rotational velocities of low-mass stars

International Nuclear Information System (INIS)

Stauffer, J.B.; Hartmann, L.W.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA)

1986-01-01

The rotational velocities of stars provide important clues to how stars form and evolve. Yet until recently, studies of stellar rotation were limited to stars more massive than the sun. This is beginning to change, and an observational outline of the rotational velocity evolution of stars less massive than the sun can now be provided. Low-mass stars rotate slowly during the early stages of premain-sequence evolution, and spin up as they contract to the main sequence. This spin-up culminates in a brief period of very rapid rotation at an age of order 50 million years. Physical interpretation of this increase in rotation and the subsequent main-sequence spin-down are complicated by the possibility of differential internal rotation. The observed rapidity of spin-down among G dwarfs suggests that initially only the outer convective envelopes of these stars are slowed. The data suggest an intrinsic spread in angular momentum among young stars of the same mass and age, a spread which is apparently minimized by the angular-momentum loss mechanism in old low-mass stars. 83 references

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.

Approaching the O{sup -} photodetachment threshold with velocity-map imaging

Energy Technology Data Exchange (ETDEWEB)

Cavanagh, S J; Gibson, S T; Lewis, B R, E-mail: Steven.Cavanagh@anu.edu.a, E-mail: Stephen.Gibson@anu.edu.a [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2009-11-01

A series of photodetachment spectra from O{sup -} has been measured from near threshold to several eV using the technique of velocity-map imaging. With a resolving power of {Delta}E/E {<=} 0.38%, the energy and angular dependences for the six fine-structure transitions have been determined. For the first time, the energy and angular dependences of the cross section within a few meV of threshold have been determined.

High-Q microsphere resonators for angular velocity sensing in gyroscopes

International Nuclear Information System (INIS)

An, Panlong; Zheng, Yongqiu; Yan, Shubin; Xue, Chenyang; Liu, Jun; Wang, Wanjun

2015-01-01

A resonator gyroscope based on the Sagnac effect is proposed using a core unit that is generated by water-hydrogen flame melting. The relationship between the quality factor Q and diameter D is revealed. The Q factor of the spectral lines of the microsphere cavity coupling system, which uses tapered fibers, is found to be 10 6 or more before packaging with a low refractive curable ultraviolet polymer, although it drops to approximately 10 5 after packaging. In addition, a rotating test platform is built, and the transmission spectrum and discriminator curves of a microsphere cavity with Q of 3.22×10 6 are measured using a semiconductor laser (linewidth less than 1 kHz) and a real-time proportional-integral circuit tracking and feedback technique. Equations fitting the relation between the voltage and angular rotation rate are obtained. According to the experimentally measured parameters, the sensitivity of the microsphere-coupled system can reach 0.095 ∘ /s

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

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.

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.

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

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°.

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.

Parameters determining maximum wind velocity in a tropical cyclone

International Nuclear Information System (INIS)

Choudhury, A.M.

1984-09-01

The spiral structure of a tropical cyclone was earlier explained by a tangential velocity distribution which varies inversely as the distance from the cyclone centre outside the circle of maximum wind speed. The case has been extended in the present paper by adding a radial velocity. It has been found that a suitable combination of radial and tangential velocities can account for the spiral structure of a cyclone. This enables parametrization of the cyclone. Finally a formula has been derived relating maximum velocity in a tropical cyclone with angular momentum, radius of maximum wind speed and the spiral angle. The shapes of the spirals have been computed for various spiral angles. (author)

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

Science.gov (United States)

Munday, Phillip M.; Taira, Kunihiko

2018-05-01

The objective of this computational study is to quantify the influence of wall-normal and angular momentum injections in suppressing laminar flow separation over a canonical airfoil. Open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at $\\alpha = 9^\\circ$ and $Re = 23,000$ is examined with large-eddy simulations. This study independently introduces wall-normal momentum and angular momentum into the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. It is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Lift enhancement and suppression of separation with the wall-normal and angular momentum inputs are characterized by modifying the standard definition of the coefficient of momentum. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With this single modified coefficient of momentum, we are able to categorize each controlled flow into separated, transitional, and attached flows.

Velocity slice imaging for dissociative electron attachment

Science.gov (United States)

Nandi, Dhananjay; Prabhudesai, Vaibhav S.; Krishnakumar, E.; Chatterjee, A.

2005-05-01

A velocity slice imaging method is developed for measuring the angular distribution of fragment negative ions arising from dissociative electron attachment (DEA) to molecules. A low energy pulsed electron gun, a pulsed field ion extraction, and a two-dimensional position sensitive detector consisting of microchannel plates and a wedge-and-strip anode are used for this purpose. Detection and storage of each ion separately for its position and flight time allows analysis of the data offline for any given time slice, without resorting to pulsing the detector bias. The performance of the system is evaluated by measuring the angular distribution of O- from O2 and comparing it with existing data obtained using conventional technique. The capability of this technique in obtaining forward and backward angular distribution data is shown to have helped in resolving one of the existing problems in the electron scattering on O2.

Active Brownian particles with velocity-alignment and active fluctuations

International Nuclear Information System (INIS)

Großmann, R; Schimansky-Geier, L; Romanczuk, P

2012-01-01

We consider a model of active Brownian particles (ABPs) with velocity alignment in two spatial dimensions with passive and active fluctuations. Here, active fluctuations refers to purely non-equilibrium stochastic forces correlated with the heading of an individual active particle. In the simplest case studied here, they are assumed to be independent stochastic forces parallel (speed noise) and perpendicular (angular noise) to the velocity of the particle. On the other hand, passive fluctuations are defined by a noise vector independent of the direction of motion of a particle, and may account, for example, for thermal fluctuations. We derive a macroscopic description of the ABP gas with velocity-alignment interaction. Here, we start from the individual-based description in terms of stochastic differential equations (Langevin equations) and derive equations of motion for the coarse-grained kinetic variables (density, velocity and temperature) via a moment expansion of the corresponding probability density function. We focus here on the different impact of active and passive fluctuations on onset of collective motion and show how active fluctuations in the active Brownian dynamics can change the phase-transition behaviour of the system. In particular, we show that active angular fluctuations lead to an earlier breakdown of collective motion and to the emergence of a new bistable regime in the mean-field case. (paper)

Velocity of lordosis angle during spinal flexion and extension.

Directory of Open Access Journals (Sweden)

Tobias Consmüller

Full Text Available The importance of functional parameters for evaluating the severity of low back pain is gaining clinical recognition, with evidence suggesting that the angular velocity of lordosis is critical for identification of musculoskeletal deficits. However, there is a lack of data regarding the range of functional kinematics (RoKs, particularly which include the changing shape and curvature of the spine. We address this deficit by characterising the angular velocity of lordosis throughout the thoracolumbar spine according to age and gender. The velocity of lumbar back shape changes was measured using Epionics SPINE during maximum flexion and extension activities in 429 asymptomatic volunteers. The difference between maximum positive and negative velocities represented the RoKs. The mean RoKs for flexion decreased with age; 114°/s (20-35 years, 100°/s (36-50 years and 83°/s (51-75 years. For extension, the corresponding mean RoKs were 73°/s, 57°/s and 47°/s. ANCOVA analyses revealed that age and gender had the largest influence on the RoKs (p<0.05. The Epionics SPINE system allows the rapid assessment of functional kinematics in the lumbar spine. The results of this study now serve as normative data for comparison to patients with spinal pathology or after surgical treatment.

Kinetic energy and angular momentum of free particles in the gyratonic pp-waves space-times

Science.gov (United States)

Maluf, J. W.; da Rocha-Neto, J. F.; Ulhoa, S. C.; Carneiro, F. L.

2018-06-01

Gyratonic pp-waves are exact solutions of Einstein’s equations that represent non-linear gravitational waves endowed with angular momentum. We consider gyratonic pp-waves that travel in the z direction and whose time dependence on the variable is given by Gaussians, so that the waves represent short bursts of gravitational radiation propagating in the z direction. We evaluate numerically the geodesics and velocities of free particles in the space-time of these waves, and find that after the passage of the waves both the kinetic energy and the angular momentum per unit mass of the particles are changed. Therefore there is a transfer of energy and angular momentum between the gravitational field and the free particles, so that the final values of the energy and angular momentum of the free particles may be smaller or larger in magnitude than the initial values.

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

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.

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.

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

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

Angular evolution of peripheral heavy ion reactions at intermediate energies

International Nuclear Information System (INIS)

Blumenfeld, Y.; Chomaz, P.; Frascaria, N.; Garron, J.P.; Jacmart, J.C; Roynette, J.C

1985-01-01

Energy spectra and angular distributions of projectile-like fragments have been measured in the vicinity of the grazing angle for the 40 Ar+ 40 Ca and 40 Ar+ 208 Pb reactions at 44MeV/nucleon. Measurements of the 40 Ar+ 40 Ca system at 27MeV/nucleon and 20 Ne+ 208 Pb reaction at 44MeV/nucleon at one angle have also been performed. For fragments with charge and mass close to the projectile numerous deviations from the standard fragmentation model have been observed including rapidly changing shapes of the angular distributions with the fragment mass. Moreover the isotopic distributions and mean fragment velocities are strongly dependent on detection angle. A surface transfer reaction component dominant at the grazing angle can be separated from a second component which cannot be entirely accounted for by a simple fragmentation mechanism

The MASSIVE Survey - V. Spatially resolved stellar angular momentum, velocity dispersion, and higher moments of the 41 most massive local early-type galaxies

Science.gov (United States)

Veale, Melanie; Ma, Chung-Pei; Thomas, Jens; Greene, Jenny E.; McConnell, Nicholas J.; Walsh, Jonelle; Ito, Jennifer; Blakeslee, John P.; Janish, Ryan

2017-01-01

We present spatially resolved two-dimensional stellar kinematics for the 41 most massive early-type galaxies (ETGs; MK ≲ -25.7 mag, stellar mass M* ≳ 1011.8 M⊙) of the volume-limited (D McDonald Observatory, covering a 107 arcsec × 107 arcsec field of view (often reaching 2 to 3 effective radii). We measure the 2D spatial distribution of each galaxy's angular momentum (λ and fast or slow rotator status), velocity dispersion (σ), and higher order non-Gaussian velocity features (Gauss-Hermite moments h3 to h6). Our sample contains a high fraction (˜80 per cent) of slow and non-rotators with λ ≲ 0.2. When combined with the lower mass ETGs in the ATLAS3D survey, we find the fraction of slow rotators to increase dramatically with galaxy mass, reaching ˜50 per cent at MK ˜ -25.5 mag and ˜90 per cent at MK ≲ -26 mag. All of our fast rotators show a clear anticorrelation between h3 and V/σ, and the slope of the anticorrelation is steeper in more round galaxies. The radial profiles of σ show a clear luminosity and environmental dependence: the 12 most luminous galaxies in our sample (MK ≲ -26 mag) are all brightest cluster/group galaxies (except NGC 4874) and all have rising or nearly flat σ profiles, whereas five of the seven `isolated' galaxies are all fainter than MK = -25.8 mag and have falling σ. All of our galaxies have positive average h4; the most luminous galaxies have average h4 ˜ 0.05, while less luminous galaxies have a range of values between 0 and 0.05. Most of our galaxies show positive radial gradients in h4, and those galaxies also tend to have rising σ profiles. We discuss the implications for the relationship among dynamical mass, σ, h4, and velocity anisotropy for these massive galaxies.

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

OpenAIRE

Justin R. Brown; Bader J. Alsarraf; Mike Waller; Patricia Eisenman; Charlie A. Hicks-Little

2014-01-01

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 i...

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

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.

Tyre effective radius and vehicle velocity estimation: a variable structure observer solution

International Nuclear Information System (INIS)

El Tannoury, C.; Plestan, F.; Moussaoui, S.; ROMANi, N. RENAULT

2011-01-01

This paper proposes an application of a variable structure observer for wheel effective radius and velocity of automotive vehicles. This observer is based on high order sliding approach allowing robustness and finite time convergence. Its originality consists in assuming a nonlinear relation between the slip ratio and the friction coefficient and providing an estimation of both variables, wheel radius and vehicle velocity, from measurement of wheel angular velocity and torque. These signals being available on major modern vehicle CAN (Controller Area Network) buses, this system does not require additional sensors. A simulation example is given to illustrate the relevance of this approach.

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.

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.

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

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.

Wind-driven angular momentum loss in binary systems. I - Ballistic case

Science.gov (United States)

Brookshaw, Leigh; Tavani, Marco

1993-01-01

We study numerically the average loss of specific angular momentum from binary systems due to mass outflow from one of the two stars for a variety of initial injection geometries and wind velocities. We present results of ballistic calculations in three dimensions for initial mass ratios q of the mass-losing star to primary star in the range q between 10 exp -5 and 10. We consider injection surfaces close to the Roche lobe equipotential surface of the mass-losing star, and also cases with the mass-losing star underfilling its Roche lobe. We obtain that the orbital period is expected to have a negative time derivative for wind-driven secular evolution of binaries with q greater than about 3 and with the mass-losing star near filling its Roche lobe. We also study the effect of the presence of an absorbing surface approximating an accretion disk on the average final value of the specific angular momentum loss. We find that the effect of an accretion disk is to increase the wind-driven angular momentum loss. Our results are relevant for evolutionary models of high-mass binaries and low-mass X-ray binaries.

Dark halos formed via dissipationless collapse. I - Shapes and alignment of angular momentum

Science.gov (United States)

Warren, Michael S.; Quinn, Peter J.; Salmon, John K.; Zurek, Wojciech H.

1992-11-01

We use N-body simulations on highly parallel supercomputers to study the structure of Galactic dark matter halos. The systems form by gravitational collapse from scale-free and more general Gaussian initial density perturbations in an expanding 400 Mpc-cubed spherical slice of an Einstein-deSitter universe. We analyze the structure and kinematics of about 100 of the largest relaxed halos in each of 10 separate simulations. A typical halo is a triaxial spheroid which tends to be more often prolate than oblate. These shapes are maintained by anisotropic velocity dispersion rather than by angular momentum. Nevertheless, there is a significant tendency for the total angular momentum vector to be aligned with the minor axis of the density distribution.

Peculiar velocity effects in high-resolution microwave background experiments

International Nuclear Information System (INIS)

Challinor, Anthony; Leeuwen, Floor van

2002-01-01

We investigate the impact of peculiar velocity effects due to the motion of the solar system relative to the cosmic microwave background (CMB) on high resolution CMB experiments. It is well known that on the largest angular scales the combined effects of Doppler shifts and aberration are important; the lowest Legendre multipoles of total intensity receive power from the large CMB monopole in transforming from the CMB frame. On small angular scales aberration dominates and is shown here to lead to significant distortions of the total intensity and polarization multipoles in transforming from the rest frame of the CMB to the frame of the solar system. We provide convenient analytic results for the distortions as series expansions in the relative velocity of the two frames, but at the highest resolutions a numerical quadrature is required. Although many of the high resolution multipoles themselves are severely distorted by the frame transformations, we show that their statistical properties distort by only an insignificant amount. Therefore, the cosmological parameter estimation is insensitive to the transformation from the CMB frame (where theoretical predictions are calculated) to the rest frame of the experiment

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.

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.

Biomechanics of increased spin velocity of flying discs during forehand throws by skilled and unskilled throwers.

Science.gov (United States)

Sasakawa, Kei; Umegaki, Koji; Sakurai, Shinji

2018-04-01

We aimed to assess the relationship between throwing distance and kinematic release parameters of the flying disc in unskilled throwers, and to assess the relationship between kinetic variables acting on flying discs and the change in spin velocity during long forehand throws by skilled and unskilled throwers. Ten skilled and eleven unskilled throwers performed throws at maximum effort. Reflective marker positions on the disc and body were recorded with a 3D motion capture system during the throws to derive kinematic variables of a disc and kinetic variables acting on the disc. The analysis interval was from maximum external shoulder rotation to disc release. Significant correlations were observed between the throwing distance and spin velocity in skilled (r = 0.722, P < 0.05) and unskilled throwers (r = 0.794, P < 0.01), between the change in spin velocity and the angular impulse of moments of force, in unskilled throwers (r = 0.703, P < 0.05), and between the change in spin velocity and the angular impulse of torque among skilled throwers (r = 0.680, P < 0.01). Therefore, a strategy for increasing spin velocity in unskilled throwers could be used to generate a larger torque, similar to that observed in skilled throwers.

HIGH-VELOCITY MOLECULAR OUTFLOW IN CO J = 7-6 EMISSION FROM THE ORION HOT CORE

International Nuclear Information System (INIS)

Furuya, Ray S.; Shinnaga, Hiroko

2009-01-01

Using the Caltech Submillimeter Observatory 10.4 m telescope, we performed sensitive mapping observations of 12 CO J = 7-6 emission at 807 GHz toward Orion IRc2. The image has an angular resolution of 10'', which is the highest angular resolution data toward the Orion Hot Core published for this transition. In addition, thanks to the on-the-fly mapping technique, the fidelity of the new image is rather high, particularly in comparison with previous images. We have succeeded in mapping the northwest-southeast high-velocity molecular outflow, whose terminal velocity is shifted by ∼70-85 km s -1 with respect to the systemic velocity of the cloud. This yields an extremely short dynamical time scale of ∼900 years. The estimated outflow mass loss rate shows an extraordinarily high value, on the order of 10 -3 M sun yr -1 . Assuming that the outflow is driven by Orion IRc2, our result agrees with the picture so far obtained for a 20 M sun (proto)star in the process of formation.

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

Sorting photons of different rotational Doppler shifts (RDS) by orbital angular momentum of single-photon with spin-orbit-RDS entanglement.

Science.gov (United States)

Chen, Lixiang; She, Weilong

2008-09-15

We demonstrate that single photons from a rotating q-plate exhibit an entanglement in three degrees of freedom of spin, orbital angular momentum, and the rotational Doppler shift (RDS) due to the nonconservation of total spin and orbital angular momenta. We find that the rotational Doppler shift deltaomega = Omega((delta)s + deltal) , where s, l and Omega are quantum numbers of spin, orbital angular momentum, and rotating velocity of the q-plate, respectively. Of interest is that the rotational Doppler shift directly reflects the rotational symmetry of q-plates and can be also expressed as deltaomega = (Omega)n , where n = 2(q-1) denotes the fold number of rotational symmetry. Besides, based on this single-photon spin-orbit-RDS entanglement, we propose an experimental scheme to sort photons of different frequency shifts according to individual orbital angular momentum.

Velocity storage contribution to vestibular self-motion perception in healthy human subjects.

Science.gov (United States)

Bertolini, G; Ramat, S; Laurens, J; Bockisch, C J; Marti, S; Straumann, D; Palla, A

2011-01-01

Self-motion perception after a sudden stop from a sustained rotation in darkness lasts approximately as long as reflexive eye movements. We hypothesized that, after an angular velocity step, self-motion perception and reflexive eye movements are driven by the same vestibular pathways. In 16 healthy subjects (25-71 years of age), perceived rotational velocity (PRV) and the vestibulo-ocular reflex (rVOR) after sudden decelerations (90°/s(2)) from constant-velocity (90°/s) earth-vertical axis rotations were simultaneously measured (PRV reported by hand-lever turning; rVOR recorded by search coils). Subjects were upright (yaw) or 90° left-ear-down (pitch). After both yaw and pitch decelerations, PRV rose rapidly and showed a plateau before decaying. In contrast, slow-phase eye velocity (SPV) decayed immediately after the initial increase. SPV and PRV were fitted with the sum of two exponentials: one time constant accounting for the semicircular canal (SCC) dynamics and one time constant accounting for a central process, known as velocity storage mechanism (VSM). Parameters were constrained by requiring equal SCC time constant and VSM time constant for SPV and PRV. The gains weighting the two exponential functions were free to change. SPV were accurately fitted (variance-accounted-for: 0.85 ± 0.10) and PRV (variance-accounted-for: 0.86 ± 0.07), showing that SPV and PRV curve differences can be explained by a greater relative weight of VSM in PRV compared with SPV (twofold for yaw, threefold for pitch). These results support our hypothesis that self-motion perception after angular velocity steps is be driven by the same central vestibular processes as reflexive eye movements and that no additional mechanisms are required to explain the perceptual dynamics.

Angular momentum independence of the entropy sum and entropy product for AdS rotating black holes in all dimensions

Directory of Open Access Journals (Sweden)

Hang Liu

2016-08-01

Full Text Available In this paper, we investigate the angular momentum independence of the entropy sum and product for AdS rotating black holes based on the first law of thermodynamics and a mathematical lemma related to Vandermonde determinant. The advantage of this method is that the explicit forms of the spacetime metric, black hole mass and charge are not needed but the Hawking temperature and entropy formula on the horizons are necessary for static black holes, while our calculations require the expressions of metric and angular velocity formula. We find that the entropy sum is always independent of angular momentum for all dimensions and the angular momentum-independence of entropy product only holds for the dimensions d>4 with at least one rotation parameter ai=0, while the mass-free of entropy sum and entropy product for rotating black holes only stand for higher dimensions (d>4 and for all dimensions, respectively. On the other hand, we find that the introduction of a negative cosmological constant does not affect the angular momentum-free of entropy sum and product but the criterion for angular momentum-independence of entropy product will be affected.

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).

Optical angular momentum and atoms

Science.gov (United States)

2017-01-01

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’. PMID:28069766

ANGULAR MOMENTUM IN GIANT MOLECULAR CLOUDS. II. M33

International Nuclear Information System (INIS)

Imara, Nia; Bigiel, Frank; Blitz, Leo

2011-01-01

We present an analysis comparing the properties of 45 giant molecular clouds (GMCs) in M33 and the atomic hydrogen (H I) with which they are associated. High-resolution Very Large Array observations are used to measure the properties of H I in the vicinity of GMCs and in regions where GMCs have not been detected. The majority of molecular clouds coincide with a local peak in the surface density of atomic gas, though 7% of GMCs in the sample are not associated with high surface density atomic gas. The mean H I surface density in the vicinity of GMCs is 10 M sun pc -2 and tends to increase with GMC mass as Σ HI ∝ M 0.27 GMC . Thirty-nine of the 45 H I regions surrounding GMCs have linear velocity gradients of ∼0.05 km s -1 pc -1 . If the linear gradients previously observed in the GMCs result from rotation, 53% are counterrotating with respect to the local H I. And if the linear gradients in these local H I regions are also from rotation, 62% are counterrotating with respect to the galaxy. If magnetic braking reduced the angular momentum of GMCs early in their evolution, the angular velocity of GMCs would be roughly one order of magnitude lower than what is observed. Based on our observations, we consider the possibility that GMCs may not be rotating. Atomic gas not associated with GMCs has gradients closer to 0.03 km s -1 pc -1 , suggesting that events occur during the course of GMC evolution that may increase the shear in the atomic gas.

Hierarchical Velocity Control Based on Differential Flatness for a DC/DC Buck Converter-DC Motor System

Directory of Open Access Journals (Sweden)

R. Silva-Ortigoza

2014-01-01

Full Text Available This paper presents a hierarchical controller that carries out the angular velocity trajectory tracking task for a DC motor driven by a DC/DC Buck converter. The high level control is related to the DC motor and the low level control is dedicated to the DC/DC Buck converter; both controls are designed via differential flatness. The high level control provides a desired voltage profile for the DC motor to achieve the tracking of a desired angular velocity trajectory. Then, a low level control is designed to ensure that the output voltage of the DC/DC Buck converter tracks the voltage profile imposed by the high level control. In order to experimentally verify the hierarchical controller performance, a DS1104 electronic board from dSPACE and Matlab-Simulink are used. The switched implementation of the hierarchical average controller is accomplished by means of pulse width modulation. Experimental results of the hierarchical controller for the velocity trajectory tracking task show good performance and robustness against the uncertainties associated with different system parameters.

Zero velocity interval detection based on a continuous hidden Markov model in micro inertial pedestrian navigation

Science.gov (United States)

Sun, Wei; Ding, Wei; Yan, Huifang; Duan, Shunli

2018-06-01

Shoe-mounted pedestrian navigation systems based on micro inertial sensors rely on zero velocity updates to correct their positioning errors in time, which effectively makes determining the zero velocity interval play a key role during normal walking. However, as walking gaits are complicated, and vary from person to person, it is difficult to detect walking gaits with a fixed threshold method. This paper proposes a pedestrian gait classification method based on a hidden Markov model. Pedestrian gait data are collected with a micro inertial measurement unit installed at the instep. On the basis of analyzing the characteristics of the pedestrian walk, a single direction angular rate gyro output is used to classify gait features. The angular rate data are modeled into a univariate Gaussian mixture model with three components, and a four-state left–right continuous hidden Markov model (CHMM) is designed to classify the normal walking gait. The model parameters are trained and optimized using the Baum–Welch algorithm and then the sliding window Viterbi algorithm is used to decode the gait. Walking data are collected through eight subjects walking along the same route at three different speeds; the leave-one-subject-out cross validation method is conducted to test the model. Experimental results show that the proposed algorithm can accurately detect different walking gaits of zero velocity interval. The location experiment shows that the precision of CHMM-based pedestrian navigation improved by 40% when compared to the angular rate threshold method.

Angular distributions of evaporation residues from near-barrier fusion of 32,36S on a ≅100 nuclei

International Nuclear Information System (INIS)

Borges, A.M.

1986-01-01

The angular distributions of evaporation residues from near-barrier fusion of 32,36 S ions with 92,94,96,98,100 Mo, 100,101,102,104 Ru, 103 Rh, and 104,105,106,108,110 Pd were measured in the range of 3 to 11 degrees in the laboratory system. The relative yield of the four most abundant exit evaporation channels has been extracted for all target-projectile combination at two bombarding energies, by fitting the angular distributions expected for each channel as obtained from the Monte-Carlo program TRANMI to the measured angular distribution of the evaporation residues. The total detection efficiency for the Munich-RF-Recoil Spectrometer was obtained from the relative yields, taking into account the effect due to multiple scattering, and compared with that obtained previously from the recoil velocity distributions. (orig./HSI) [de

Instrument for measuring flow velocities

International Nuclear Information System (INIS)

Griffo, J.

1977-01-01

The design described here means to produce a 'more satisfying instrument with less cost' than comparable instruments known up to now. Instead of one single turbine rotor, two similar ones but with opposite blade inclination and sense of rotation are to be used. A cylindrical measuring body is carrying in its axis two bearing blocks whose shape is offering little flow resistance. On the shaft, supported by them, the two rotors run in opposite direction a relatively small axial distance apart. The speed of each rotor is picked up as pulse recurrence frequency by a transmitter and fed to an electronic measuring unit. Measuring errors as they are caused for single rotors by turbulent flow, profile distortion of the velocity, or viscous flow are to be eliminated by means of the contrarotating turbines and the subsequently added electronic unit, because in these cases the adulterating increase of the angular velocity of one rotor is compensated by a corresponding deceleration of the other rotor. The mean value then indicated by the electronic unit has high accurancy of measurement. (RW) [de

Angular Momentum in Dwarf Galaxies

Directory of Open Access Journals (Sweden)

Del Popolo A.

2014-06-01

Full Text Available We study the “angular momentum catastrophe” in the framework of interaction among baryons and dark matter through dynamical friction. By means of Del Popolo (2009 model we simulate 14 galaxies similar to those investigated by van den Bosch, Burkert and Swaters (2001, and calculate the distribution of their spin parameters and the angular momenta. Our model gives the angular momentum distribution which is in agreement with the van den Bosch et al. observations. Our result shows that the “angular momentum catastrophe” can be naturally solved in a model that takes into account the baryonic physics and the exchange of energy and angular momentum between the baryonic clumps and dark matter through dynamical friction.

Angular Momentum and Galaxy Formation Revisited

Science.gov (United States)

Romanowsky, Aaron J.; Fall, S. Michael

2012-12-01

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 sstarf and mass M sstarf (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 sstarf reliably. Our results contravene suggestions that ellipticals could harbor large reservoirs of hidden j sstarf 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 sstarf versus M sstarf. The ellipticals and spirals form two parallel j sstarf-M sstarf 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 sstarf-M sstarf 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 sstarf

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.

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.

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.

Angular momentum of dwarf galaxies

Science.gov (United States)

Kurapati, Sushma; Chengalur, Jayaram N.; Pustilnik, Simon; Kamphuis, Peter

2018-05-01

Mass and specific angular momentum are two fundamental physical parameters of galaxies. We present measurements of the baryonic mass and specific angular momentum of 11 void dwarf galaxies derived from neutral hydrogen (HI) synthesis data. Rotation curves were measured using 3D and 2D tilted ring fitting routines, and the derived curves generally overlap within the error bars, except in the central regions where, as expected, the 3D routines give steeper curves. The specific angular momentum of void dwarfs is found to be high compared to an extrapolation of the trends seen for higher mass bulge-less spirals, but comparable to that of other dwarf irregular galaxies that lie outside of voids. As such, our data show no evidence for a dependence of the specific angular momentum on the large scale environment. Combining our data with the data from the literature, we find a baryonic threshold of ˜109.1 M⊙ for this increase in specific angular momentum. Interestingly, this threshold is very similar to the mass threshold below which the galaxy discs start to become systematically thicker. This provides qualitative support to the suggestion that the thickening of the discs, as well as the increase in specific angular momentum, are both results of a common physical mechanism, such as feedback from star formation. Quantitatively, however, the amount of star formation observed in our dwarfs appears insufficient to produce the observed increase in specific angular momentum. It is hence likely that other processes, such as cold accretion of high angular momentum gas, also play a role in increasing the specific angular momentum.

Angular response of hot wire probes

International Nuclear Information System (INIS)

Di Mare, L; Jelly, T O; Day, I J

2017-01-01

A new equation for the convective heat loss from the sensor of a hot-wire probe is derived which accounts for both the potential and the viscous parts of the flow past the prongs. The convective heat loss from the sensor is related to the far-field velocity by an expression containing a term representing the potential flow around the prongs, and a term representing their viscous effect. This latter term is absent in the response equations available in the literature but is essential in representing some features of the observed response of miniature hot-wire probes. The response equation contains only four parameters but it can reproduce, with great accuracy, the behaviour of commonly used single-wire probes. The response equation simplifies the calibration the angular response of rotated slanted hot-wire probes: only standard King’s law parameters and a Reynolds-dependent drag coefficient need to be determined. (paper)

The Csub(N) method in cylindrical geometry and one-velocity theory

International Nuclear Information System (INIS)

Kavenoky, A.

1975-01-01

The Csub(N) method of solving the transport equation has been developed at Saclay during the last few years: its main advantage is that the computing time is independent of the size of the media considered. This method is based on a lemma proved by Placzek: an integral equation is provided for the angular flux at the boundaries of the media, its kernel is the infinite medium Green's function. The knowledge of the angular flux at the boundaries of the media allows the fluxes to be calculated at any point. The report is devoted to the application to classical problems in one velocity cylindrical geometry: albedo of the inner and outer problems, extrapolation length for the Milne problem, critical radius [fr

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

Do Assimilated Drifter Velocities Improve Lagrangian Predictability in an Operational Ocean Model?

Science.gov (United States)

2015-05-01

extended Kalman filter . Molcard et al. (2005) used a statistical method to cor- relate model and drifter velocities. Taillandier et al. (2006) describe the... temperature and salinity observations. Trajectory angular differ- ences are also reduced. 1. Introduction The importance of Lagrangian forecasts was seen... Temperature , salinity, and sea surface height (SSH, measured along-track by satellite altimeters) observa- tions are typically assimilated in

Nonlinear dynamic model for skidding behavior of angular contact ball bearings

Science.gov (United States)

Han, Qinkai; Chu, Fulei

2015-10-01

A three-dimensional nonlinear dynamic model is proposed to predict the skidding behavior of angular contact ball bearings under combined load condition. The centrifugal and gyroscopic effects induced by ball rotation and revolution, Hertz contact between the ball and inner/outer races, discontinuous contact between the ball and cage and elastohydrodynamic lubrication are considered in the model. Through comparisons with the tested results of the reference, the dynamic model is verified. Based upon these, variations of ball slipping speed with time and space are discussed for the bearing under combined load condition. It is shown that radial load leads to the fluctuations in the slipping velocity of the ball contacting with inner/outer races, especially for the ball in load-decreasing regions. Adding the radial load would significantly increase the amplitude and range of slipping velocity, indicating that the skidding becomes more serious. As the ball still withstands contact load in the load-decreasing region, large slipping velocity would increase the temperature of both bearing and lubricant oil, intensify the wear and then might shorten the bearing service life. Therefore, the radial load should be considered carefully in the design and monitoring of rotating machinery.

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

Directory of Open Access Journals (Sweden)

Elliot Leader

2018-04-01

Full Text Available 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. Keywords: Photon, Angular momentum, Laser optics, Particle physics

AngularJS : yksisivuisen web-sovelluksen käyttöliittymän toteutus AngularJS:llä

OpenAIRE

Suomijoki, Juha

2015-01-01

Opinnäytetyössä tutkittiin mikä on AngularJS-JavaScript-ohjelmistokehys ja miten se soveltuu yksisivuisen web-sovelluksen käyttöliittymän toteutukseen. AngularJS on vuonna 2012 julkaistu Googlen ylläpitämä JavaScript-ohjelmistokehys, joka on tarkoitettu ensisijaisesti yksisivuisten web-sovellusten kehittämiseen. Opinnäytetyön teoriaosuudessa tutkittiin mikä AngularJS on ja mitkä ovat AngularJS:n keskeiset konseptit ja sovelluskomponentit. Tarkastelu pohjautui AngularJS:stä kirjoitettu...

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.

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...

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

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

Three-dimensional trajectory tracking for underactuated AUVs with bio-inspired velocity regulation

Directory of Open Access Journals (Sweden)

Jiajia Zhou

2018-05-01

Full Text Available This paper attempts to address the motion parameter skip problem associated with three-dimensional trajectory tracking of an underactuated Autonomous Underwater Vehicle (AUV using backstepping-based control, due to the unsmoothness of tracking trajectory. Through kinematics concepts, a three-dimensional dynamic velocity regulation controller is derived. This controller makes use of the surge and angular velocity errors with bio-inspired models and backstepping techniques. It overcomes the frequently occurring problem of parameter skip at inflection point existing in backstepping tracking control method and increases system robustness. Moreover, the proposed method can effectively avoid the singularity problem in backstepping control of virtual velocity error. The control system is proved to be uniformly ultimately bounded using Lyapunov stability theory. Simulation results illustrate the effectiveness and efficiency of the developed controller, which can realize accurate three-dimensional trajectory tracking for an underactuated AUV with constant external disturbances. Keywords: Dynamic velocity regulation, Bio-inspired model, Backstepping, Underactuated AUV, Three-dimensional trajectory tracking

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.

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.

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.

Radial profiles of velocity and pressure for condensation-induced hurricanes

Science.gov (United States)

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

2011-02-01

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.

Radial profiles of velocity and pressure for condensation-induced hurricanes

Energy Technology Data Exchange (ETDEWEB)

Makarieva, A.M., E-mail: ammakarieva@gmail.co [Theoretical Physics Division, Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Gorshkov, V.G. [Theoretical Physics Division, Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation)

2011-02-14

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.

AngularJS Performance: A Survey Study

OpenAIRE

Ramos, Miguel; Valente, Marco Tulio; Terra, Ricardo

2017-01-01

AngularJS is a popular JavaScript MVC-based framework to construct single-page web applications. In this paper, we report the results of a survey with 95 professional developers about performance issues of AngularJS applications. We report common practices followed by developers to avoid performance problems (e.g., use of third-party or custom components), the general causes of performance problems in AngularJS applications (e.g., inadequate architecture decisions taken by AngularJS users), a...

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.

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

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

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

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.

Angular-momentum transport in nuclear collisions

International Nuclear Information System (INIS)

Wolschin, G.; Ayik, S.; Noerenberg, W.

1978-01-01

Among the various relaxation processes that can be observed in heavy-ion collisions, the dissipation of relative angular momentum into intrinsic angular momentum of the fragments attracts increasing attention. Here we present a transport theoretical description of angular-momentum and mass transport that allows for a transparent interpretation of the data. (orig.) [de

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.

Comparison of positronium, positron and electron collisions with hydrogen at low velocities

International Nuclear Information System (INIS)

Reeth, P Van; Humberston, J W; Woods, Denton; Ward, S J

2016-01-01

Recent experimental findings indicate that at equal velocity electron and ortho-positronium scattering cross sections are similar over a wide range of velocities and targets where both elastic and inelastic processes can take place. We present a comparative study of positronium, positron and electron elastic scattering from atomic hydrogen in order to investigate if a similar behaviour occurs for this target at low velocities where inelastic channels are closed. We calculate elastic cross sections for the three projectiles using Kohn-type variational methods which allows us to make a detailed study of the differences and similarities. We find a qualitative similarity in the spin-weighted elastic integrated cross sections for positronium and electron scattering and a good agreement between the singlet integrated cross sections. However, this agreement does extend to the low velocity region and where the agreement is found in the integrated cross sections we show that it is not present in the individual partial waves cross sections. Interestingly, given the agreement we find in the singlet integrated cross section for electron and positronium scattering, when comparing the overall shapes of the corresponding singlet differential cross sections we find different angular and velocity dependencies. (paper)

Natural roller bearing fault detection by angular measurement of true instantaneous angular speed

Science.gov (United States)

Renaudin, L.; Bonnardot, F.; Musy, O.; Doray, J. B.; Rémond, D.

2010-10-01

The challenge in many production activities involving large mechanical devices like power transmissions consists in reducing the machine downtime, in managing repairs and in improving operating time. Most online monitoring systems are based on conventional vibration measurement devices for gear transmissions or bearings in mechanical components. In this paper, we propose an alternative way of bearing condition monitoring based on the instantaneous angular speed measurement. By the help of a large experimental investigation on two different applications, we prove that localized faults like pitting in bearing generate small angular speed fluctuations which are measurable with optical or magnetic encoders. We also emphasize the benefits of measuring instantaneous angular speed with the pulse timing method through an implicit angular sampling which ensures insensitivity to speed fluctuation. A wide range of operating conditions have been tested for the two applications with varying speed, load, external excitations, gear ratio, etc. The tests performed on an automotive gearbox or on actual operating vehicle wheels also establish the robustness of the proposed methodology. By the means of a conventional Fourier transform, angular frequency channels kinematically related to the fault periodicity show significant magnitude differences related to the damage severity. Sideband effects are evidently seen when the fault is located on rotating parts of the bearing due to load modulation. Additionally, slip effects are also suspected to be at the origin of enlargement of spectrum peaks in the case of double row bearings loaded in a pure radial direction.

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

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.

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

Angular trap for macroparticles

International Nuclear Information System (INIS)

Aksyonov, D.S.

2013-01-01

Properties of angular macroparticle traps were investigated in this work. These properties are required to design vacuum arc plasma filters. The correlation between trap geometry parameters and its ability to absorb macroparticles were found. Calculations allow one to predict the behaviour of filtering abilities of separators which contain such traps in their design. Recommendations regarding the use of angular traps in filters of different builds are given.

Angular momentum in general relativity

International Nuclear Information System (INIS)

Cresswell, A.; Zimmerman, R.L.; Oregon Univ., Eugene

1986-01-01

It is argued that the correct expressions for the angular momentum flux carried by gravitational radiation should follow directly from the momentum currents. Following this approach, the authors compute the angular momentum associated with several different choices of energy-momentum prescriptions. (author)

A kinetic theory for nonanalog Monte Carlo algorithms: Exponential transform with angular biasing

International Nuclear Information System (INIS)

Ueki, T.; Larsen, E.W.

1998-01-01

A new Boltzmann Monte Carlo (BMC) equation is proposed to describe the transport of Monte Carlo particles governed by a set of nonanalog rules for the transition of space, velocity, and weight. The BMC equation is a kinetic equation that includes weight as an extra independent variable. The solution of the BMC equation is the pointwise distribution of velocity and weight throughout the physical system. The BMC equation is derived for the simulation of a transmitted current, utilizing the exponential transform with angular biasing. The weight moments of the solution of the BMC equation are used to predict the score moments of the transmission current. (Also, it is shown that an adjoint BMC equation can be used for this purpose.) Integrating the solution of the forward BMC equation over space, velocity, and weight, the mean number of flights per history is obtained. This is used to determine theoretically the figure of merit for any choice of biasing parameters. Also, a maximum safe value of the exponential transform parameter is proposed, which ensure the finite variance of variance estimate (sample variance) for any penetration distance. Finally, numerical results that validate the new theory are provided

角动量的理论研究%Theoretical Studies on Angular Momentum

Institute of Scientific and Technical Information of China (English)

尹芬芬

2015-01-01

研究一些物理问题时,我们会遇到质点或质点系相对于参考点或绕轴转动的情况,此时用速度、动量都不能解决,因此物理学中引入了新的物理量—角动量.角动量能准确地描述物体的转动状况,在量子领域中也能反映表征状态,并且在现代技术中有着广泛的应用.本文从角动量的定义出发,对质点对参考点、质点绕定轴、质点系绕定轴等不同情况下的角动量定理及守恒定律进行了研究,并对动量守恒和角动量守恒的区别与联系以及角动量的知识应用等进行了探讨.%In physics, mass points or mass point systems may revolve relative to the reference point or around the axis. In this case, neither velocity nor momentum can solve it, but angular momentum, a new physical concept of physics, is introduced, which precisely describes the revolution of an object, reflects its representational state in the quantum realm, and is therefore widely used in modern technologies. Based on the definition of angular momentum, this article studies the angular momentum theorems and the conservation laws governing in different circumstances such as the mass point relative to the reference point, the mass point around the fixed axis, the mass point system around the fixed axis, etc, and further probes the differences and commonality between momentum conservation and angular momentum conservation, and the application of angular momentum.

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

THE EFFECTS OF ANGULAR MOMENTUM ON HALO PROFILES

Energy Technology Data Exchange (ETDEWEB)

Lentz, Erik W; Rosenberg, Leslie J [Physics Department, University of Washington, Seattle, WA 98195-1580 (United States); Quinn, Thomas R, E-mail: lentze@phys.washington.edu, E-mail: ljrosenberg@phys.washington.edu, E-mail: trq@astro.washington.edu [Astronomy Department, University of Washington, Seattle, WA 98195-1580 (United States)

2016-05-10

The near universality of DM halo density profiles provided by N -body simulations proved to be robust against changes in total mass density, power spectrum, and some forms of initial velocity dispersion. Here we study the effects of coherently spinning up an isolated DM-only progenitor on halo structure. Halos with spins within several standard deviations of the simulated mean ( λ ≲ 0.20) produce profiles with negligible deviations from the universal form. Only when the spin becomes quite large ( λ ≳ 0.20) do departures become evident. The angular momentum distribution also exhibits a near universal form, which is also independent of halo spin up to λ ≲ 0.20. A correlation between these epidemic profiles and the presence of a strong bar in the virialized halo is also observed. These bar structures bear resemblance to the radial orbit instability in the rotationless limit.

A quasi-one-dimensional velocity regime of super-thermal electron stream propagation through the solar corona

International Nuclear Information System (INIS)

Levin, B.N.

1984-01-01

The propagation of an inhomogeneous stream of fast electrons through the corona - the type III radio burst source - is considered. It is shown, that the angular spectrum width of plasma waves excited by the stream is defined both by Landau damping by particles of the diffuse component and by damping (in the region of large phase velocities) by particles of the stream itself having large pitch angles. The regime of quasi-one-dimensional diffusion in the velocity space is realized only in the presence of a sufficiently dense diffuse component of super-thermal particles and only for a sufficiently large inhomogeneity scale of the stream. A large scale of the stream space profile is formed, evidently, close to the region of injection of super-thermal particles. It is the result of 'stripping' of part of the electrons from the stream front to its slower part due to essential non-one-dimensionality of the particle diffusion in velocity space. Results obtained may explain, in particular, the evolution of a stream particle angular spectrum in the generation region of type III radio bursts observed by spacecrafts (Lin et al., 1981). For the relatively low energetic part of the stream, the oblique plasma wave stabilization by a diffuse component results in a quasi-one-dimensional regime of diffusion. The latter conserves the beam-like structure of this part of the stream. (orig.)

Development of a beam ion velocity detector for the heavy ion beam probe

International Nuclear Information System (INIS)

Fimognari, P. J.; Crowley, T. P.; Demers, D. R.

2016-01-01

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.

Development of a beam ion velocity detector for the heavy ion beam probe

Energy Technology Data Exchange (ETDEWEB)

Fimognari, P. J., E-mail: PJFimognari@XanthoTechnologies.com; Crowley, T. P.; Demers, D. R. [Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States)

2016-11-15

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.

Orbital angular momentum in phase space

International Nuclear Information System (INIS)

Rigas, I.; Sanchez-Soto, L.L.; Klimov, A.B.; Rehacek, J.; Hradil, Z.

2011-01-01

Research highlights: → We propose a comprehensive Weyl-Wigner formalism for the canonical pair angle-angular momentum. → We present a simple and useful toolkit for the practitioner. → We derive simple evolution equations in terms of a star product in the semiclassical limit. - Abstract: A comprehensive theory of the Weyl-Wigner formalism for the canonical pair angle-angular momentum is presented. Special attention is paid to the problems linked to rotational periodicity and angular-momentum discreteness.

Angular momentum projected wave-functions

International Nuclear Information System (INIS)

Bengtsson, R.; Haakansson, H.B.

1978-01-01

Angular momentum projection has become a vital link between intrinsic model-wavefunctions and the physical states one intends to describe. We discuss in general terms some aspects of angular momentum projection and present results from projection on e.g. cranking wavefunctions. Mass densities and spectroscopic factors are also presented for some cases. (author)

About the velocity operator for spinning particles in quantum mechanics

Energy Technology Data Exchange (ETDEWEB)

Salesi, Giovanni [Universita Statale di Catania (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Catania (Italy); Recami, Erasmo; Rodrigues Junior, Waldyr A. [Universidade Estadual de Campinas, SP (Brazil). Dept. de Matematica Aplicada

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.

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

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.

Management of Angular Cheilitis in children

Directory of Open Access Journals (Sweden)

Fajriani Fajriani

2017-04-01

Full Text Available Objective : Angular cheilitis is a type of oral soft tissue disease that can occur in children and adults, the condition is characterized by cracks and inflammation on both corners of the mouth. Although this disease can not cause severe disorder, it quite disturbs one's activity and physical appearance. Mild Angular cheilitis will recover itself over times. However severe conditions can cause pain and bleeding. This paper aims to inform colleagues about management of angular cheilitis in children.

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.

High angular resolution at LBT

Science.gov (United States)

Conrad, A.; Arcidiacono, C.; Bertero, M.; Boccacci, P.; Davies, A. G.; Defrere, D.; de Kleer, K.; De Pater, I.; Hinz, P.; Hofmann, K. H.; La Camera, A.; Leisenring, J.; Kürster, M.; Rathbun, J. A.; Schertl, D.; Skemer, A.; Skrutskie, M.; Spencer, J. R.; Veillet, C.; Weigelt, G.; Woodward, C. E.

2015-12-01

High angular resolution from ground-based observatories stands as a key technology for advancing planetary science. In the window between the angular resolution achievable with 8-10 meter class telescopes, and the 23-to-40 meter giants of the future, LBT provides a glimpse of what the next generation of instruments providing higher angular resolution will provide. We present first ever resolved images of an Io eruption site taken from the ground, images of Io's Loki Patera taken with Fizeau imaging at the 22.8 meter LBT [Conrad, et al., AJ, 2015]. We will also present preliminary analysis of two data sets acquired during the 2015 opposition: L-band fringes at Kurdalagon and an occultation of Loki and Pele by Europa (see figure). The light curves from this occultation will yield an order of magnitude improvement in spatial resolution along the path of ingress and egress. We will conclude by providing an overview of the overall benefit of recent and future advances in angular resolution for planetary science.

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...

Angular integrals in d dimensions.

OpenAIRE

Somogyi, G.

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.

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.

Angular integrals in d dimensions

Science.gov (United States)

Somogyi, Gábor

2011-08-01

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.

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.)

Angular momentum exchange by gravitational torques and infall in the circumbinary disk of the protostellar system L1551 NE

Energy Technology Data Exchange (ETDEWEB)

Takakuwa, Shigehisa; Ho, Paul T. P. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Saito, Masao [Joint ALMA Observatory, Ave. Alonso de Cordova 3107, Vitacura, Santiago (Chile); Saigo, Kazuya [ALMA Project Office, National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan); Matsumoto, Tomoaki [Faculty of Humanity and Environment, Hosei University, Chiyoda-ku, Tokyo 102-8160 (Japan); Lim, Jeremy [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Hanawa, Tomoyuki, E-mail: takakuwa@asiaa.sinica.edu.tw [Center for Frontier Science, Chiba University, Inage-ku, Chiba 263-8522 (Japan)

2014-11-20

We report an ALMA observation of the Class I binary protostellar system L1551 NE in the 0.9 mm continuum, C{sup 18}O (3-2), and {sup 13}CO (3-2) lines at a ∼1.6 times higher resolution and a ∼6 times higher sensitivity than those of our previous SubMillimeter Array (SMA) observations, which revealed a r ∼ 300 AU scale circumbinary disk in Keplerian rotation. The 0.9 mm continuum shows two opposing U-shaped brightenings in the circumbinary disk and exhibits a depression between the circumbinary disk and the circumstellar disk of the primary protostar. The molecular lines trace non-axisymmetric deviations from Keplerian rotation in the circumbinary disk at higher velocities relative to the systemic velocity, where our previous SMA observations could not detect the lines. In addition, we detect inward motion along the minor axis of the circumbinary disk. To explain the newly observed features, we performed a numerical simulation of gas orbits in a Roche potential tailored to the inferred properties of L1551 NE. The observed U-shaped dust features coincide with locations where gravitational torques from the central binary system are predicted to impart angular momentum to the circumbinary disk, producing shocks and hence density enhancements seen as a pair of spiral arms. The observed inward gas motion coincides with locations where angular momentum is predicted to be lowered by the gravitational torques. The good agreement between our observation and model indicates that gravitational torques from the binary stars constitute the primary driver for exchanging angular momentum so as to permit infall through the circumbinary disk of L1551 NE.

Angular integrals in d dimensions

Energy Technology Data Exchange (ETDEWEB)

Somogyi, Gabor

2011-01-15

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.)

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.)

Velocity Spread Reduction for Axis-encircling Electron Beam Generated by Single Magnetic Cusp

Science.gov (United States)

Jeon, S. G.; Baik, C. W.; Kim, D. H.; Park, G. S.; Sato, N.; Yokoo, K.

2001-10-01

Physical characteristics of an annular Pierce-type electron gun are investigated analytically. An annular electron gun is used in conjunction with a non-adiabatic magnetic reversal and an adiabatic compression to produce an axis-encircling electron beam. Velocity spread close to zero is realized with an initial canonical angular momentum spread at the cathode when the beam trajectory does not coincide with the magnetic flux line. Both the analytical calculation and the EGUN code simulation confirm this phenomenon.

Scaling laws for the rotational velocity of a J x B driven rotating plasma

International Nuclear Information System (INIS)

Igarashi, Yasuhito; Kataoka, Tomohiro; Ikehata, Takashi; Sato, Naoyuki; Tanabe, Toshio; Mase, Hiroshi

1994-01-01

Rapidly rotating plasmas of helium and argon have been extracted from a coaxial plasma gun operated in pulsed glow mode. The rotational velocity and its parametric dependence have been analyzed systematically by means of visible - emission spectroscopy. The plasma is observed to rotate rigidly inside the diameter of the gun anode while outside the velocity decreases rapidly ; furthermore, different ions are found to rotate at different angular frequencies as ω (Ar + ) = 0.5 x 10 6 rad/sec, ω (Ar 2+ ) = 1.1 x 10 6 rad/sec, ω (C 2+ ) = 1.8 x 10 6 rad/sec, ω (N + ) = 1.2 x 10 6 rad/sec. The plasma density and rotational velocity have been measured as a function of the discharge current and magnetic field to derive experimental scaling laws. They are summarized as : 1. Ion density is proportional to the square of discharge current. 2. Rotational and axial velocities are proportional to the driving force per ion. These results are confirmed to agree well with a theoretical prediction. (author)

Velocity dependence of transient hyperfine field at Pt ions rapidly recoiling through magnetized Fe

International Nuclear Information System (INIS)

Stuchbery, A.E.; Ryan, C.G.; Bolotin, H.H.

1981-01-01

The velocity-dependence of the transient hyperfine magnetic field acting at nuclei of 196 Pt ions rapidly recoiling through thin magnetized Fe was investigated at a number of recoil velocities. The state of interest (2 1 + ) was populated by Coulomb excitation using beams of 80- and 120-MeV 32 S and 150- and 220-MeV 58 Ni ions. The 2 1 + →0 1 + γ-ray angular distribution precession measurements were carried out in coincidence with backscattered projectiles. From these results, the strength of the transient field acting on Pt ions recoiling through magnetized Fe with average velocities in the extended range 2.14<=v/vsub(o)<=4.82 (vsub(o) = c/137) was found to be consistent with a linear velocity dependence and to be incompatible with the specific vsup(0.45+-0.18) dependence which has been previously reported to account well for all ions in the mass range from oxygen through samarium. This seemingly singular behaviour for Pt and other ions in the Pt mass vicinity is discussed

Optimal centralized and decentralized velocity feedback control on a beam

International Nuclear Information System (INIS)

Engels, W P; Elliott, S J

2008-01-01

This paper considers the optimization of a velocity feedback controller with a collocated force actuator, to minimize the kinetic energy of a simply supported beam. If the beam is excited at a single location, the optimum feedback gain varies with the position of the control system. It is shown that this variation depends partly on the location of the control force relative to the exciting force. If a distributed excitation is assumed, that is random in both time and space, a unique optimum value of the feedback gain can be found for a given control location. The effect of the control location on performance and the optimal feedback gain can then be examined and is found to be limited provided the control locations are not close to the ends of the beam. The optimization can also be performed for a multichannel velocity feedback system. Both a centralized and a decentralized controller are considered. It is shown that the difference in performance between a centralized and a decentralized controller is small, unless the control locations are closely spaced. In this case the centralized controller effectively feeds back a moment proportional to angular velocity as well as a force proportional to a velocity. It is also shown that the optimal feedback gain can be approximated on the basis of a limited model and that similar results can be achieved

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.

[NEII] Line Velocity Structure of Ultracompact HII Regions

Science.gov (United States)

Okamoto, Yoshiko K.; Kataza, Hirokazu; Yamashita, Takuya; Miyata, Takashi; Sako, Shigeyuki; Honda, Mitsuhiko; Onaka, Takashi; Fujiyoshi, Takuya

Newly formed massive stars are embedded in their natal molecular clouds and are observed as ultracompact HII regions. They emit strong ionic lines such as [NeII] 12.8 micron. Since Ne is ionized by UV photons of E>21.6eV which is higher than the ionization energy of hydrogen atoms the line probes the ionized gas near the ionizing stars. This enables to probe gas motion in the vicinity of recently-formed massive stars. High angular and spectral resolution observations of the [NeII] line will thus provide siginificant information on structures (e.g. disks and outflows) generated through massive star formation. We made [NeII] spectroscopy of ultracompact HII regions using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2m Subaru Telescope in July 2002. Spatial and spectral resolutions were 0.5"" and 10000 respectively. Among the targets G45.12+0.13 shows the largest spatial variation in velocity. The brightest area of G45.12+0.13 has the largest line width in the object. The total velocity deviation amounts to 50km/s (peak to peak value) in the observed area. We report the velocity structure of [NeII] emission of G45.12+0.13 and discuss the gas motion near the ionizing star.

Recoil velocity at second post-Newtonian order for spinning black hole binaries

International Nuclear Information System (INIS)

Racine, Etienne; Buonanno, Alessandra; Kidder, Larry

2009-01-01

We compute the flux of linear momentum carried by gravitational waves emitted from spinning binary black holes at second post-Newtonian (2PN) order for generic orbits. In particular we provide explicit expressions of three new types of terms, namely, next-to-leading order spin-orbit terms at 1.5 post-Newtonian (1.5PN) order, spin-orbit tail terms at 2PN order, and spin-spin terms at 2PN order. Restricting ourselves to quasicircular orbits, we integrate the linear-momentum flux over time to obtain the recoil velocity as function of orbital frequency. We find that in the so-called superkick configuration the higher-order spin corrections can increase the recoil velocity up to a factor ∼3 with respect to the leading-order PN prediction. Whereas the recoil velocity computed in PN theory within the adiabatic approximation can accurately describe the early inspiral phase, we find that its fast increase during the late inspiral and plunge, and the arbitrariness in determining until when it should be trusted, makes the PN predictions for the total recoil not very accurate and robust. Nevertheless, the linear-momentum flux at higher PN orders can be employed to build more reliable resummed expressions aimed at capturing the nonperturbative effects until merger. Furthermore, we provide expressions valid for generic orbits, and accurate at 2PN order, for the energy and angular momentum carried by gravitational waves emitted from spinning binary black holes. Specializing to quasicircular orbits we compute the spin-spin terms at 2PN order in the expression for the evolution of the orbital frequency and found agreement with Mikoczi, Vasuth, and Gergely. We also verified that in the limit of extreme mass ratio our expressions for the energy and angular momentum fluxes match the ones of Tagoshi, Shibata, Tanaka, and Sasaki obtained in the context of black hole perturbation theory.

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%

A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey

Science.gov (United States)

Westmeier, Tobias

2018-02-01

High-velocity clouds (HVCs) are neutral or ionized gas clouds in the vicinity of the Milky Way that are characterized by high radial velocities inconsistent with participation in the regular rotation of the Galactic disc. Previous attempts to create a homogeneous all-sky H I map of HVCs have been hampered by a combination of poor angular resolution, limited surface brightness sensitivity and suboptimal sampling. Here, a new and improved H I map of Galactic HVCs based on the all-sky HI4PI survey is presented. The new map is fully sampled and provides significantly better angular resolution (16.2 versus 36 arcmin) and column density sensitivity (2.3 versus 3.7 × 1018 cm-2 at the native resolution) than the previously available LAB survey. The new HVC map resolves many of the major HVC complexes in the sky into an intricate network of narrow H I filaments and clumps that were not previously resolved by the LAB survey. The resulting sky coverage fraction of high-velocity H I emission above a column density level of 2 × 1018 cm-2 is approximately 15 per cent, which reduces to about 13 per cent when the Magellanic Clouds and other non-HVC emission are removed. The differential sky coverage fraction as a function of column density obeys a truncated power law with an exponent of -0.93 and a turnover point at about 5 × 1019 cm-2. H I column density and velocity maps of the HVC sky are made publicly available as FITS images for scientific use by the community.

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.

Whole-body angular momentum during stair ascent and descent.

Science.gov (United States)

Silverman, Anne K; Neptune, Richard R; Sinitski, Emily H; Wilken, Jason M

2014-04-01

The generation of whole-body angular momentum is essential in many locomotor tasks and must be regulated in order to maintain dynamic balance. However, angular momentum has not been investigated during stair walking, which is an activity that presents a biomechanical challenge for balance-impaired populations. We investigated three-dimensional whole-body angular momentum during stair ascent and descent and compared it to level walking. Three-dimensional body-segment kinematic and ground reaction force (GRF) data were collected from 30 healthy subjects. Angular momentum was calculated using a 13-segment whole-body model. GRFs, external moment arms and net joint moments were used to interpret the angular momentum results. The range of frontal plane angular momentum was greater for stair ascent relative to level walking. In the transverse and sagittal planes, the range of angular momentum was smaller in stair ascent and descent relative to level walking. Significant differences were also found in the ground reaction forces, external moment arms and net joint moments. The sagittal plane angular momentum results suggest that individuals alter angular momentum to effectively counteract potential trips during stair ascent, and reduce the range of angular momentum to avoid falling forward during stair descent. Further, significant differences in joint moments suggest potential neuromuscular mechanisms that account for the differences in angular momentum between walking conditions. These results provide a baseline for comparison to impaired populations that have difficulty maintaining dynamic balance, particularly during stair ascent and descent. Copyright © 2014 Elsevier B.V. All rights reserved.

ANGULAR MOMENTUM ACQUISITION IN GALAXY HALOS

International Nuclear Information System (INIS)

Stewart, Kyle R.; Brooks, Alyson M.; Bullock, James S.; Maller, Ariyeh H.; Diemand, Jürg; Wadsley, James; Moustakas, Leonidas A.

2013-01-01

We use high-resolution cosmological hydrodynamic simulations to study the angular momentum acquisition of gaseous halos around Milky-Way-sized galaxies. We find that cold mode accreted gas enters a galaxy halo with ∼70% more specific angular momentum than dark matter averaged over cosmic time (though with a very large dispersion). In fact, we find that all matter has a higher spin parameter when measured at accretion than when averaged over the entire halo lifetime, and is well characterized by λ ∼ 0.1, at accretion. Combined with the fact that cold flow gas spends a relatively short time (1-2 dynamical times) in the halo before sinking to the center, this naturally explains why cold flow halo gas has a specific angular momentum much higher than that of the halo and often forms ''cold flow disks.'' We demonstrate that the higher angular momentum of cold flow gas is related to the fact that it tends to be accreted along filaments.

Orbital angular momentum exchange in post-collision interaction

International Nuclear Information System (INIS)

van der Burgt, P.J.M.; van Eck, J.; Heideman, H.G.M.

1985-01-01

The authors study the exchange of orbital angular mementum between the scattered and the ejected electron. The angular distribution of electrons ejected by the He (2s 2 ) 2 S autoionizing state after its excitation via the He (2s2p 2 ) 2 D resonance is measured. Taking into accout interference with electrons from the direct ionization of helium, the authors are able to show that the measured anisotropic angular distribution is the result of an orbital angular momentum exchange during the post-collision interaction

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…

What Do the Hitomi Observations Tell Us About the Turbulent Velocities in the Perseus Cluster? Probing the Velocity Field with Mock Observations

Science.gov (United States)

ZuHone, J. A.; Miller, E. D.; Bulbul, E.; Zhuravleva, I.

2018-02-01

Hitomi made the first direct measurements of galaxy cluster gas motions in the Perseus cluster, which implied that its core is fairly “quiescent,” with velocities less than ∼200 km s‑1, despite the presence of an active galactic nucleus and sloshing cold fronts. Building on previous work, we use synthetic Hitomi/X-ray Spectrometer (SXS) observations of the hot plasma of a simulated cluster with sloshing gas motions and varying viscosity to analyze its velocity structure in a similar fashion. We find that sloshing motions can produce line shifts and widths similar to those measured by Hitomi. We find these measurements are unaffected by the value of the gas viscosity, since its effects are only manifested clearly on angular scales smaller than the SXS ∼1‧ PSF. The PSF biases the line shift of regions near the core as much as ∼40–50 km s‑1, so it is crucial to model this effect carefully. We also infer that if sloshing motions dominate the observed velocity gradient, Perseus must be observed from a line of sight that is somewhat inclined from the plane of these motions, but one that still allows the spiral pattern to be visible. Finally, we find that assuming isotropy of motions can underestimate the total velocity and kinetic energy of the core in our simulation by as much as ∼60%. However, the total kinetic energy in our simulated cluster core is still less than 10% of the thermal energy in the core, in agreement with the Hitomi observations.

Angular distributions in quasi-fission reactions

International Nuclear Information System (INIS)

Luetzenkirchen, K.; Kratz, J.V.; Lucas, R.; Poitou, J.; Gregoire, C.; Wirth, G.; Bruechle, W.; Suemmerer, K.

1985-10-01

Angular distributions for fission-like fragments were measured in the systems 50 Ti, 56 Fe + 208 Pb by applying an off-line KX-ray activation technique. The distributions d 2 sigma/dTHETAdZ exhibit forward-backward asymmetries that are strongly Z-dependent. They result from a process (quasi-fission) which yields nearly symmetric masses in times comparable to the rotational period of the composite system. A method for obtaining the variance of the tilting angular momentum, K 0 2 , from these skewed, differential angular distributions is described. The results indicate that the tilting mode is not fully excited in quasi-fission reactions. The results are compared to the sum of the variances of all statistical spin components, measured via γ-multiplicities. Integration of the angular distributions d 2 sigma/dTHETAdZ over all values of Z yields integral angular distributions dsigma/dTHETA and dsigma/dΩ symmetric around 90 0 . The associated unusually large anisotropies do not at all provide an adequate basis for tests or modifications of the transition state theory. A deconvolution of d 2 sigma/dTHETAdZ is performed with gaussian distributions depending on rotational angles ΔTHETA extending over a range of up to 540 0 . From the mean values a time scale for the evolution of K 0 is calculated. (orig.)

Photon beam polarization and non-dipolar angular distributions

International Nuclear Information System (INIS)

Peshkin, M.

1996-01-01

Angular distributions of ejecta from unoriented atoms and molecules depend upon the polarization state of the incident x-rays as well as upon the dynamics of the physical systems being studied. I recommend a simple geometrical way of looking at the polarization and its effects upon angular distributions. The polarization is represented as a vector in a parameter space that faithfully represents the polarization of the beam. The simple dependence of the angular dependence of the angular distributions on the polarization vector enables easy extraction of the dynamical information contained in those angular distributions. No new physical results emerge from this geometrical approach, but known consequences of the symmetries appear in an easily visualized form that I find pleasing and that has proved to be useful for planning experiments and for analyzing data

Beam Angular Divergence Effects in Ion Implantation

International Nuclear Information System (INIS)

Horsky, T. N.; Hahto, S. K.; Bilbrough, D. G.; Jacobson, D. C.; Krull, W. A.; Goldberg, R. D.; Current, M. I.; Hamamoto, N.; Umisedo, S.

2008-01-01

An important difference between monomer ion beams and heavy molecular beams is a significant reduction in beam angular divergence and increased on-wafer angular accuracy for molecular beams. This advantage in beam quality stems from a reduction in space-charge effects within the beam. Such improved angular accuracy has been shown to have a significant impact on the quality and yield of transistor devices [1,12]. In this study, B 18 H x + beam current and angular divergence data collected on a hybrid scanned beam line that magnetically scans the beam across the wafer is presented. Angular divergence is kept below 0.5 deg from an effective boron energy of 200 eV to 3000 eV. Under these conditions, the beam current is shown analytically to be limited by space charge below about 1 keV, but by the matching of the beam emittance to the acceptance of the beam line above 1 keV. In addition, results of a beam transport model which includes variable space charge compensation are presented, in which a drift mode B 18 H x + beam is compared to an otherwise identical boron beam after deceleration. Deceleration is shown to introduce significant space-charge blow up resulting in a large on-wafer angular divergence. The divergence effects introduced by wafer charging are also discussed.

Rotationally resolved photodetachment spectrum of OH{sup -}, exposed with velocity-map imaging

Energy Technology Data Exchange (ETDEWEB)

Gibson, S T; Cavanagh, S J; Lewis, B R, E-mail: Stephen.Gibson@anu.edu.a, E-mail: Steven.Cavanagh@anu.edu.a [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2009-11-01

The photodetachment spectrum of OH{sup -} has been measured using velocity-map imaging for the detection of photoelectrons. The relative electron kinetic-energy resolution, determined to be ({Delta}E/E) = 0.5%, resolves individual rotational transitions, including R3(0) that defines the electron affinity. Previously unobserved, N-, O-, S-, T-branch transitions are also revealed. The angular anisotropy parameters in general exhibit values consistent with electron detachment from O{sup -}, {beta} {approx} -0.8, except for the S, T branches which are significantly more isotropic, with {beta} {approx} -0.4.

Ghost Imaging Using Orbital Angular Momentum

Institute of Scientific and Technical Information of China (English)

赵生妹; 丁建; 董小亮; 郑宝玉

2011-01-01

We present a novel encoding scheme in a ghost-imaging system using orbital angular momentum. In the signal arm, object spatial information is encoded as a phase matrix. For an N-grey-scale object, different phase matrices, varying from 0 to K with increment n/N, are used for different greyscales, and then they are modulated to a signal beam by a spatial light modulator. According to the conservation of the orbital angular momentum in the ghost imaging system, these changes will give different coincidence rates in measurement, and hence the object information can be extracted in the idler arm. By simulations and experiments, the results show that our scheme can improve the resolution of the image effectively. Compared with another encoding method using orbital angular momentum, our scheme has a better performance for both characters and the image object.%We present a novel encoding scheme in a ghost-imaging system using orbital angular momentum.In the signal arm,object spatial information is encoded as a phase matrix.For an N-grey-scale object,different phase matrices,varying from 0 to π with increment π/N,are used for different greyscales,and then they are modulated to a signal beam by a spatial light modulator.According to the conservation of the orbital angular momentum in the ghost imaging system,these changes will give different coincidence rates in measurement,and hence the object information can be extracted in the idler arm.By simulations and experiments,the results show that our scheme can improve the resolution of the image effectively.Compared with another encoding method using orbital angular momentum,our scheme has a better performance for both characters and the image object.

Angular momentum in general relativity

International Nuclear Information System (INIS)

Prior, C.R.

1977-01-01

The definition of angular momentum proposed in part I of this series (Prior. Proc. R. Soc. Lond.; A354:379 (1977)) is investigated when applied to rotating black holes. It is shown how to use the formula to evaluate the angular momentum of a stationary black hole. This acts as a description of a background space on which the effect of first matter and then gravitational perturbations is considered. The latter are of most interest and the rate of change of angular momentum, dJ/dt, is found as an expression in the shear induced in the event horizon by the perturbation and in its time integral. Teukolsky's solutions (Astrophys. J.; 185:635 (1973)) for the perturbed component of the Weyl tensor are then used to find this shear and hence to give an exact answer for dJ/dt. One of the implications of the result is a direct verification of Bekenstein's formula (Phys. Rev.; 7D:949 (1973)) relating in a simple way the rate of change of angular momentum to the rate of change of mass caused by a plane wave. A more general expression is also given for dM/dt. Considering only stationary perturbations, it is shown how to generalize the definition of angular momentum so as to include information about its direction as well. Three problems are particularly discussed - a single moon, two or more moons and a ring of matter causing the perturbation - since they provide illustrations of all the main features of the black hole's behaviour. In every case it is found that the black hole realigns its axis of rotation so that the final configuration is axisymmetric if possible; otherwise is slows down completely to reach a static state. (author)

Jet angularity measurements for single inclusive jet production

Science.gov (United States)

Kang, Zhong-Bo; Lee, Kyle; Ringer, Felix

2018-04-01

We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in- and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

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.

Staggering of angular momentum distribution in fission

Science.gov (United States)

Tamagno, Pierre; Litaize, Olivier

2018-03-01

We review here the role of angular momentum distributions in the fission process. To do so the algorithm implemented in the FIFRELIN code [?] is detailed with special emphasis on the place of fission fragment angular momenta. The usual Rayleigh distribution used for angular momentum distribution is presented and the related model derivation is recalled. Arguments are given to justify why this distribution should not hold for low excitation energy of the fission fragments. An alternative ad hoc expression taking into account low-lying collectiveness is presented as has been implemented in the FIFRELIN code. Yet on observables currently provided by the code, no dramatic impact has been found. To quantify the magnitude of the impact of the low-lying staggering in the angular momentum distribution, a textbook case is considered for the decay of the 144Ba nucleus with low excitation energy.

Mixed optical Cherenkov–Bremsstrahlung radiation in vicinity of the Cherenkov cone from relativistic heavy ions: Unusual dependence of the angular distribution width on the radiator thickness

Energy Technology Data Exchange (ETDEWEB)

Rozhkova, E.I., E-mail: elenafiks@gmail.com; Pivovarov, Yu.L.

2016-07-15

The Cherenkov radiation (ChR) angular distribution is usually described by the Tamm–Frank (TF) theory, which assumes that relativistic charged particle moves uniformly and rectilinearly in the optically transparent radiator. According to the TF theory, the full width at half maximum (FWHM) of the ChR angular distribution inversely depends on the radiator thickness. In the case of relativistic heavy ions (RHI) a slowing-down in the radiator may sufficiently change the angular distribution of optical radiation in vicinity of the Cherenkov cone, since there appears a mixed ChR–Bremsstrahlung radiation. As a result, there occurs a drastic transformation of the FWHM of optical radiation angular distribution in dependence on the radiator thickness: from inversely proportional (TF theory) to the linearly proportional one. In our paper we present the first analysis of this transformation taking account of the gradual velocity decrease of RHI penetrating through a radiator. - Highlights: • Stopping of relativistic heavy ions leads to appearance of a Cherenkov–Bremsstrahlung radiation near the Cherenkov cone. • Mixed Cherenkov–Bremsstrahlung optical radiation FWHM differs from the standard one determined by the Tamm–Frank theory. • The Cherenkov–Bremsstrahlung radiation angular distribution FWHM linearly depends on the radiator thickness.

Fluid dynamics of air in a packed bed: velocity profiles and the continuum model assumption

Directory of Open Access Journals (Sweden)

NEGRINI A. L.

1999-01-01

Full Text Available Air flow through packed beds was analyzed experimentally under conditions ranging from those that reinforce the effect of the wall on the void fraction to those that minimize it. The packing was spherical particles, with a tube-to-particle diameter ratio (D/dp between 3 and 60. Air flow rates were maintained between 1.3 and 4.44 m3/min, and gas velocity was measured with a Pitot tube positioned above the bed exit. Measurements were made at various radial and angular coordinate values, allowing the distribution of air flow across the bed to be described in detail. Comparison of the experimentally observed radial profiles with those derived from published equations revealed that at high D/dp ratios the measured and calculated velocity profiles behaved similarly. At low ratios, oscillations in the velocity profiles agreed with those in the voidage profiles, signifying that treating the porous medium as a continuum medium is questionable in these cases.

Exposing Library Services with AngularJS

OpenAIRE

Jakob Voß; Moritz Horn

2014-01-01

This article provides an introduction to the JavaScript framework AngularJS and specific AngularJS modules for accessing library services. It shows how information such as search suggestions, additional links, and availability can be embedded in any website. The ease of reuse may encourage more libraries to expose their services via standard APIs to allow usage in different contexts.

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.

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

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

Accelerated rotation with orbital angular momentum modes

CSIR Research Space (South Africa)

Schulze, C

2015-04-01

Full Text Available . As the angular acceleration takes place in a bounded space, the azimuthal degree of freedom, such fields accelerate periodically as they propagate. Notably, the amount of angular acceleration is not limited by paraxial considerations, may be tailored for large...

Staggering of angular momentum distribution in fission

Directory of Open Access Journals (Sweden)

Tamagno Pierre

2018-01-01

Full Text Available We review here the role of angular momentum distributions in the fission process. To do so the algorithm implemented in the FIFRELIN code [?] is detailed with special emphasis on the place of fission fragment angular momenta. The usual Rayleigh distribution used for angular momentum distribution is presented and the related model derivation is recalled. Arguments are given to justify why this distribution should not hold for low excitation energy of the fission fragments. An alternative ad hoc expression taking into account low-lying collectiveness is presented as has been implemented in the FIFRELIN code. Yet on observables currently provided by the code, no dramatic impact has been found. To quantify the magnitude of the impact of the low-lying staggering in the angular momentum distribution, a textbook case is considered for the decay of the 144Ba nucleus with low excitation energy.

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.

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)

Angular distributions in pre-equilibrium reactions

International Nuclear Information System (INIS)

Chatterjee, A.; Gupta, S.K.; Bhabha Atomic Research Centre, Bombay

1982-10-01

A new model is proposed for calculating angular distributions in preequilibrium reactions. In this model, as in the model of Feshbach et al. the system consisting of target plus projectile initially branches into two sets of states with either no particle in the continuum (multistep compound states) or with at least one particle in the continuum (multistep direct states). The two chains of states are treated independently by solving two sets of master equations. The multistep compound emission is assumed to be isotropic while the angular distribution of the multistep direct emission is described using the fast particle model of Mantzouranis et al. The angular distributions for 14.6 MeV neutrons calculated using this model are found to be in better agreement with the data than the fast particle model. (author)

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.

Performance Investigation of Air Velocity Effects on PV Modules under Controlled Conditions

Directory of Open Access Journals (Sweden)

Muzaffar Ali

2017-01-01

Full Text Available Junction temperature of PV modules is one of the key parameters on which the performance of PV modules depends. In the present work, an experimental investigation was carried out to analyze the effects of air velocity on the performance of two PV modules, that is, monocrystalline silicon and polycrystalline silicon under the controlled conditions of a wind tunnel in the presence of an artificial solar simulator. The parameters investigated include the surface temperature variation, power output, and efficiency of PV modules under varying air velocity from near zero (indoor lab. conditions to 15 m/s. Additionally, the results were also determined at two different module angular positions: at 0° angle, that is, parallel to air direction and at 10° angle with the direction of coming air to consider the effects of tilt angles. Afterwards, the thermal analysis of the modules was performed using Ansys-Fluent in which junction temperature and heat flux of modules were determined by applying appropriate boundary conditions, such as air velocity, heat flux, and solar radiation. Finally, the numerical results are compared with the experiment in terms of junction temperatures of modules and good agreement was found. Additionally, the results showed that the maximum module temperature drops by 17.2°C and the module efficiency and power output increased from 10 to 12% with increasing air velocity.

Determination of the excitation energy and angular momentum of the quasi-projectiles produced in the heavy ion collisions Xe + Sn

International Nuclear Information System (INIS)

Genouin-Duhamel, Emmanuel

1999-01-01

This work is a contribution to the study of properties of hot nuclei formed in heavy ion collisions at intermediate energies. The experiment has been performed with the INDRA multidetector. It is shown that most of the reaction cross section is associated with binary dissipative collisions, accompanied by the production of particles from a region between the two reaction partners. This study is focussed on excitation energy and angular momentum of projectile-like fragment (PLF) in 129 Xe + nat Sn reactions from 25 to 50 MeV per nucleon. Several methods are used to characterize hot nuclei (velocity, charge, mass and excitation energy). All these methods are compared between them and indicate that high energies are deposited in the nuclei during collision (it may exceed the nucleus binding energy). The angular momentum transferred into intrinsic spin to PLF in the peripheral collisions has been deduced from angular distributions and kinetic energies of the emitted light charged particles (atomic number smaller ar equal to 2). Both methods agree qualitatively. The spin values decrease with the violence of the collision. These values correspond to values averaged over the whole deexcitation chain of nuclei. The predictions of transport models reproduce qualitatively the most peripheral collisions and suggest that high spins are transferred to PLF (from 30 to 50 ℎ). Larger angular momentum values are observed at the lowest incident energy. The time hierarchy in the evaporation process and the role of mid-rapidity emission are also discussed. (author)

Manifest rotation symmetric expressions for angular momentum eigenfunctions

International Nuclear Information System (INIS)

Eeg, J.O.; Wroldsen, J.

1983-01-01

Manifest rotation symmetric expressions for eigenfunctions for spin s, orbital angular momentum l and total angular momentum j = l+s, .... , /l-s/ in terms of (2j+1) x (2s+1) multipole transition matrices (MTM) is given. These matrices, which are irreducible tensor matrices, have an algebra together with ordinary spin matrices for spin s and spin j. Explicit expressions for MTM's and their algebra are given for angular momenta <-3. By means of some examples it is shown that within this formalism angular integrations in central field problems will be simplified considerably. Thus the formalism turns out to be very useful for instance for calculations within the MIT-bag and also within spin-spin interactions in atomic physics. (Auth.)

The angular momentum dependence of complex fragment emission

International Nuclear Information System (INIS)

Sobtka, L.G.; Sarantites, D.G.; Li, Z.

1987-01-01

Large fragment (A > 4) production at high angular momentum is studied via the reaction, 200 MeV 45 Sc + 65 Cu. Comparisons of the fragment yields from this reaction (high angular momentum) to those from 93 Nb + Be (low angular momentum) are used to verify the strong angular momentum dependence of large fragment production predicted by equilibrium models. Details of the coincident γ-ray distributions not only confirm a rigidly rotating intermediate but also indicate that the widths of the primary L-wave distributions decrease with increasing symmetry in the decay channel. These data are used to test the asymmetry and L-wave dependence of emission barriers calculated from a rotating, finite range corrected, liquid drop model. 21 refs., 10 figs

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...

Primordial inhomogeneities in the expanding universe. I - Density and velocity distributions of galaxies in the vicinities of rich clusters

Science.gov (United States)

Silk, J.; Wilson, M. L.

1979-01-01

The density profiles and Hubble flow deviations in the vicinities of rich galaxy clusters are derived for a variety of models of initial density and velocity perturbations at the recombination epoch. The galaxy correlation function, measured with respect to the Abell clusters, is used to normalize the theoretical models. The angular scales of the required primordial inhomogeneities are calculated. It is found that the resulting density profiles around rich clusters are surprisingly insensitive to the shape of the initial perturbations and also to the cosmological density parameter, Omega. However, it is shown that the distribution of galaxy radial velocities can provide a possible means of deriving Omega.

Angular momentum conservation for uniformly expanding flows

International Nuclear Information System (INIS)

Hayward, Sean A

2007-01-01

Angular momentum has recently been defined as a surface integral involving an axial vector and a twist 1-form, which measures the twisting around the spacetime due to a rotating mass. The axial vector is chosen to be a transverse, divergence-free, coordinate vector, which is compatible with any initial choice of axis and integral curves. Then a conservation equation expresses the rate of the change of angular momentum along a uniformly expanding flow as a surface integral of angular momentum densities, with the same form as the standard equation for an axial Killing vector, apart from the inclusion of an effective energy tensor for gravitational radiation

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.

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.

Angular cheilitis: A clinical and microbial study

Directory of Open Access Journals (Sweden)

Nirima Oza

2017-01-01

Full Text Available Aims: The aim of the present study was to examine clinical types and microbiological flora isolated from angular chelitis. Materials and Methods: An eroded and/or erythematous, with or without fissure formation, nonvesicular lesion radiating from the angle of the mouth was considered to be angular chelitis. A sample of the present study comprised of 40 patients having unilateral or bilateral angular chelitis and 20 healthy individuals without any lip lesions. Clinical examination was done. In both test and control groups, the sample for microbial analysis was obtained from angle of the mouth. Results: Clinically, four types of angular cheilitis lesions were found, Type I, II, III, and IV. The most common type of lesion found was Type I lesion. Microorganisms isolated from the lesion were Staphylococcus aureus, Candida or Streptococci in 33 (82.5% cases either in pure culture or mixed culture. Among these 33 patients, S. aureus was found in 25 (75.5% cases, Candida in 16 (48.4% cases, and Streptococci in 5 (13.5% cases, respectively. Out of 16 cases positive for Candida, in 13 cases further isolation of Candida was possible. Candida albicans was found in 6 cases and Candida stellastodia in 7 cases. In majority of the dentulous and edentulous patients, S. aureus showed profuse growth. Conclusions: There are microorganisms associated with angular cheilitis.

A peculiar distribution of radial velocities of faint radio-galaxies with 13.0<=msub(corr)<=15.5

International Nuclear Information System (INIS)

Karoji, H.; Nottale, L.; Vigier, J.-P.

1976-01-01

A sample of 41 radio-galaxies with 13.0<=msub(corr)<=15.5 has been analyzed to test the angular redshift anisotropy discovered on Sc I galaxies by Rubin, Rubin and Ford (1973). The sample does not present their anisotropy but contains an even more curious distribution of radial velocities which suggests that the Rubin-Ford effect results from an anomalous redshift of light when it travels through clusters of galaxies. (Auth.)

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.

Angular Spectra of Polarized Galactic Foregrounds

OpenAIRE

Cho, Jung; Lazarian, A.

2003-01-01

It is believed that magnetic field lines are twisted and bend by turbulent motions in the Galaxy. Therefore, both Galactic synchrotron emission and thermal emission from dust reflects statistics of Galactic turbulence. Our simple model of Galactic turbulence, motivated by results of our simulations, predicts that Galactic disk and halo exhibit different angular power spectra. We show that observed angular spectra of synchrotron emission are compatible with our model. We also show that our mod...

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.

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.

Valence and inner-valence shell dissociative photoionization of CO in the 26-33 eV range. II. Molecular-frame and recoil-frame photoelectron angular distributions

DEFF Research Database (Denmark)

Lebech, M.; Houver, J.C.; Raseev, G.

2012-01-01

Experimental and theoretical results for molecular-frame photoemission are presented for inner-valence shell photoionization of the CO molecule induced by linearly and circularly polarized light. The experimental recoil frame photoelectron angular distributions (RFPADs) obtained from dissociative...... photoionization measurements where the velocities of the ionic fragment and photoelectron were detected in coincidence, are compared to RFPADs computed using the multichannel Schwinger configuration interaction method. The formalism for including a finite lifetime of the predissociative ion state is presented...... for the case of general elliptically polarized light, to obtain the RFPAD rather than the molecular frame photoelectron angular distribution (MFPAD), which would be obtained with the assumption of instantaneous dissociation. We have considered photoionization of CO for the photon energies of 26.0 eV, 29.5 e...

Angular dispersion and deflection function for heavy ion elastic scattering

International Nuclear Information System (INIS)

Bai Zhen; Han Jianlong; Hu Zhengguo; Chinese Academy of Sciences, Beijing

2007-01-01

The differential cross sections for elastic scattering products of 17 F on 208 Pb have been measured. The angular dispersion plots of ln(dσ/dθ) versus θ 2 are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nuclear rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena. (authors)

Frame dependence of spin-one angular conditions in light front dynamics

International Nuclear Information System (INIS)

Bakker, Bernard L. G.; Ji Chuengryong

2002-01-01

We elaborate the frame dependence of the angular conditions for spin-1 form factors. An extra angular condition is found in addition to the usual angular condition relating the four helicity amplitudes. Investigating the frame dependence of angular conditions, we find that the extra angular condition is in general as complicated as the usual one, although it becomes very simple in the q + =0 frame involving only two helicity amplitudes. It is confirmed that the angular conditions are identical in frames that are connected by kinematical transformations. The high-Q 2 behavior of the physical form factors and the limiting behavior in special reference frames are also discussed

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

Consequences of high effective Prandtl number on solar differential rotation and convective velocity

Science.gov (United States)

Karak, Bidya Binay; Miesch, Mark; Bekki, Yuto

2018-04-01

Observations suggest that the large-scale convective velocities obtained by solar convection simulations might be over-estimated (convective conundrum). One plausible solution to this could be the small-scale dynamo which cannot be fully resolved by global simulations. The small-scale Lorentz force suppresses the convective motions and also the turbulent mixing of entropy between upflows and downflows, leading to a large effective Prandtl number (Pr). We explore this idea in three-dimensional global rotating convection simulations at different thermal conductivity (κ), i.e., at different Pr. In agreement with previous non-rotating simulations, the convective velocity is reduced with the increase of Pr as long as the thermal conductive flux is negligible. A subadiabatic layer is formed near the base of the convection zone due to continuous deposition of low entropy plumes in low-κ simulations. The most interesting result of our low-κ simulations is that the convective motions are accompanied by a change in the convection structure that is increasingly influenced by small-scale plumes. These plumes tend to transport angular momentum radially inward and thus establish an anti-solar differential rotation, in striking contrast to the solar rotation profile. If such low diffusive plumes, driven by the radiative-surface cooling, are present in the Sun, then our results cast doubt on the idea that a high effective Pr may be a viable solution to the solar convective conundrum. Our study also emphasizes that any resolution of the conundrum that relies on the downward plumes must take into account the angular momentum transport and heat transport.

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.

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)

Generation of angular-momentum-dominated electron beams from a photoinjector

International Nuclear Information System (INIS)

Sun, Yin-E.; Piot, Philippe; Kim, Kwang-Je; Barov, Nikolas; Lidia, Steven; Santucci, James; Tikhoplav, Rodion; Wennerberg, Jason

2004-01-01

Various projects under study require an angular-momentum-dominated electron beam generated by a photoinjector. Some of the proposals directly use the angular-momentum-dominated beams (e.g. electron cooling of heavy ions), while others require the beam to be transformed into a flat beam (e.g. possible electron injectors for light sources and linear colliders). In this paper, we report our experimental study of an angular-momentum-dominated beam produced in a photoinjector, addressing the dependencies of angular momentum on initial conditions. We also briefly discuss the removal of angular momentum. The results of the experiment, carried out at the Fermilab/NICADD Photoinjector Laboratory, are found to be in good agreement with theoretical and numerical models

Nuclear spin measurement using the angular correlation method

International Nuclear Information System (INIS)

Schapira, J.-P.

The double angular correlation method is defined by a semi-classical approach (Biendenharn). The equivalence formula in quantum mechanics are discussed for coherent and incoherent angular momentum mixing; the correlations are described from the density and efficiency matrices (Fano). The ambiguities in double angular correlations can be sometimes suppressed (emission of particles with a high orbital momentum l), using triple correlations between levels with well defined spin and parity. Triple correlations are applied to the case where the direction of linear polarization of γ-rays is detected [fr

Notes on the quantum theory of angular momentum

CERN Document Server

Feenberg, Eugene

1999-01-01

This classic, concise text has served a generation of physicists as an exceptionally useful guide to the mysteries of angular momenta and Clebsch-Gordon Coefficients. Derived from notes originally prepared to assist graduate students in reading research papers on atomic, molecular, and nuclear structure, the text first reviews the basic elements of quantum theory. It then examines the development of the fundamental commutation relations for angular momentum components and vector operators, and the ways in which matrix elements and eigenvalues of the angular momentum operators are worked out f

Spherical Harmonic Analysis of Particle Velocity Distribution Function: Comparison of Moments and Anisotropies using Cluster Data

Science.gov (United States)

Gurgiolo, Chris; Vinas, Adolfo F.

2009-01-01

This paper presents a spherical harmonic analysis of the plasma velocity distribution function using high-angular, energy, and time resolution Cluster data obtained from the PEACE spectrometer instrument to demonstrate how this analysis models the particle distribution function and its moments and anisotropies. The results show that spherical harmonic analysis produced a robust physical representation model of the velocity distribution function, resolving the main features of the measured distributions. From the spherical harmonic analysis, a minimum set of nine spectral coefficients was obtained from which the moment (up to the heat flux), anisotropy, and asymmetry calculations of the velocity distribution function were obtained. The spherical harmonic method provides a potentially effective "compression" technique that can be easily carried out onboard a spacecraft to determine the moments and anisotropies of the particle velocity distribution function for any species. These calculations were implemented using three different approaches, namely, the standard traditional integration, the spherical harmonic (SPH) spectral coefficients integration, and the singular value decomposition (SVD) on the spherical harmonic methods. A comparison among the various methods shows that both SPH and SVD approaches provide remarkable agreement with the standard moment integration method.

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.

Angular momentum alignment in molecular beam scattering

International Nuclear Information System (INIS)

Treffers, M.A.

1985-01-01

It is shown how the angular momentum alignment in a molecular beam can be determined using laser-induced fluorescence in combination with precession of the angular momenta in a magnetic field. After a general analysis of the method, some results are presented to illustrate the possibilities of the method. Experimental data are presented on the alignment production for Na 2 molecules that made a collision induced angular momentum transition. Magnitude as well as direction of the alignment have been determined for scattering with several scattering partners and for a large number of scattering angles and transitions. The last chapter deals with the total alignment production in a final J-state, i.e. without state selection of the initial rotational state. (orig.)

Yksisivuisten web-sovellusten kehittäminen Angular 2 -sovelluskehyksellä

OpenAIRE

Kujala, Miika

2016-01-01

Yksisivuiset web-sovellukset ovat yleistyneet viime vuosina. Niiden kehityksessä hyödynnetään usein JavaScript-sovelluskehystä. Angular 2 on Google:n kehittämä JavaScript-sovelluskehys. Tämän tutkielman tavoitteena on tarkastella Angular 2 -sovelluskehystä ja sen soveltuvuutta yksisivuisten web-sovellusten ke- hityksessä. Tutkielmassa käydään läpi Angular 2 -sovelluskehyksen ominaisuuksia sekä Angular 2 -sovelluskehyksen käytössä ilmeneviä etuja ja haittoja.

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%.

Angular Accelerating White Light

CSIR Research Space (South Africa)

Dudley, Angela L

2015-08-01

Full Text Available wavelength dependence. By digitally simulating free-space propagation on the SLM, The authors compare the effects of real and digital propagation on the angular rotation rates of the resulting optical fields for various wavelengths. The development...

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

Angular momentum dependence of the distribution of shell model eigenenergies

International Nuclear Information System (INIS)

Yen, M.K.

1974-01-01

In the conventional shell model calculation the many-particle energy matrices are constructed and diagonalized for definite angular momentum and parity. However the resulting set of eigenvalues possess a near normal behavior and hence a simple statistical description is possible. Usually one needs only about four parameters to capture the average level densities if the size of the set is not too small. The parameters are essentially moments of the distribution. But the difficulty lies in the yet unsolved problem of calculating moments in the fixed angular momentum subspace. We have derived a formula to approximate the angular momentum projection dependence of any operator averaged in a shell model basis. This approximate formula which is a truncated series in Hermite polynomials has been proved very good numerically and justified analytically for large systems. Applying this formula to seven physical cases we have found that the fixed angular momentum projection energy centroid, width and higher central moments can be obtained accurately provided for even-even nuclei the even and odd angular momentum projections are treated separately. Using this information one can construct the energy distribution for fixed angular momentum projection assuming normal behavior. Then the fixed angular momentum level densities are deduced and spectra are extracted. Results are in reasonably good agreement with the exact values although not as good as those obtained using exact fixed angular momentum moments. (Diss. Abstr. Int., B)

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.

AngularJS yksisivuisen web-applikaation kehitysalustana

OpenAIRE

Karhu, Tuomo

2015-01-01

Yksisivuiset web-applikaatiot (SPA-sovellukset) ovat yleistyneet viimeisten kymmenen vuoden aikana, ja näiden avulla on ollut mahdollista tuoda verkkosivuston käyttökokemus lähemmäksi aitojen ohjelmasovellusten vastaavaa. Yksisivuisten web-applikaatioitten kehitystyöhön tarkoitetuista sovelluskehyksistä AngularJS on yksi käytetyimmistä ja suosituimmista. Työn tavoitteena on selvittää miten AngularJS-sovelluskehys soveltuu SPA-sivustojen kehitykseen sovelluskehittäjän näkökulmasta, sekä mi...

Measurement of angular distribution of cosmic-ray muon fluence rate

International Nuclear Information System (INIS)

Lin, Jeng-Wei; Chen, Yen-Fu; Sheu, Rong-Jiun; Jiang, Shiang-Huei

2010-01-01

In this work a Berkeley Lab cosmic ray detector was used to measure the angular distribution of the cosmic-ray muon fluence rate. Angular response functions of the detector at each measurement orientation were calculated by using the FLUKA Monte Carlo code, where no energy attenuation was taken into account. Coincidence counting rates were measured at ten orientations with equiangular intervals. The muon angular fluence rate spectrum was unfolded from the measured counting rates associated with the angular response functions using both the MAXED code and the parameter adjusting method.

Angular momentum content of galaxies

International Nuclear Information System (INIS)

Shaya, E.J.; Tully, R.B.

1984-01-01

A schema of galaxy formation is developed in which the environmental influence of large-scale structure plays a dominant role. This schema was motivated by the observation that the fraction of E and S0 galaxies is much higher in clusters than in low-density regions and by an inference that those spirals that are found in clusters probably have fallen in relatively recently from the low-density regions. It is proposed that the tidal field of the Local Supercluster acts to determine the morphology of galaxies through two complementary mechanisms. In the first place, the supercluster can apply torques to protogalaxies. Galaxies which collapsed while expanding away from the central cluster decoupled from the external tidal field and conserved the angular momentum that they acquired before collapse. Galaxies which formed in the cluster while the cluster collapsed continued to feel the tidal field. In the latter case, the spin of outer collapsing layers can be halted and reversed, and tends to cancel the spin of inner layers. The result is a reduction of the total angular momentum content of the galaxy. In addition, the supercluster tidal field can regulate accretion of fresh material onto the galaxies since the field creates a Roche limit about galaxies and material beyond this limit is lost. Any material that has not collapsed onto a galaxy by the time the galaxy falls into a cluster will be tidally stripped. The angular momentum content of that part of the protogalactic cloud which has not yet collapsed . continues to grow linearly with time due to the continued torquing by the supercluster and neighbors. Galaxies at large distances from the cluster core can continue to accrete this high angular momentum material until the present, but galaxies that enter the cluster are cut off from replenishing material

QCD angular correlations for muon pair production

International Nuclear Information System (INIS)

Kajantie, K.; Raitio, R.; Lindfors, J.

1978-01-01

Angular distributions of muons are discussed in the framework of a QCD treatment of muon pair production in hadron-hadron collisions. The predicted angular effects are independent of the infrared behavior of QCD. Measuring them will permit one to determine whether the origin of the large transverse momentum of the pair is in the quark transverse momenta or in a constituent-constituent subprocess. (author)

Electronic orbital angular momentum and magnetism of graphene

Energy Technology Data Exchange (ETDEWEB)

Luo, Ji, E-mail: ji.luo@upr.edu

2014-10-01

Orbital angular momentum (OAM) of graphene electrons in a perpendicular magnetic field is calculated and corresponding magnetic moment is used to investigate the magnetism of perfect graphene. Variation in magnetization demonstrates its decrease with carrier-doping, plateaus in a large field, and de Haas–van Alphen oscillation. Regulation of graphene's magnetism by a parallel electric field is presented. The OAM originates from atomic-scale electronic motion in graphene lattice, and vector hopping interaction between carbon atomic orbitals is the building element. A comparison between OAM of graphene electrons, OAM of Dirac fermions, and total angular momentum of the latter demonstrates their different roles in graphene's magnetism. Applicability and relation to experiments of the results are discussed. - Highlights: • Orbital angular momentum of graphene electrons is calculated. • Orbital magnetic moment of graphene electrons is obtained. • Variation in magnetization of graphene is calculated. • Roles of different kinds of angular momentum are investigated.

THE MEGAMASER COSMOLOGY PROJECT. V. AN ANGULAR-DIAMETER DISTANCE TO NGC 6264 AT 140 Mpc

International Nuclear Information System (INIS)

Kuo, C. Y.; Braatz, J. A.; Lo, K. Y.; Condon, J. J.; Impellizzeri, C. M. V.; Reid, M. J.; Henkel, C.

2013-01-01

We present the direct measurement of the Hubble constant, yielding the direct measurement of the angular-diameter distance to NGC 6264 using the H 2 O megamaser technique. Our measurement is based on sensitive observations of the circumnuclear megamaser disk from four observations with the Very Long Baseline Array, the Green Bank Telescope (GBT), and the Effelsberg telescope. We also monitored the maser spectral profile for 2.3 years using the GBT to measure accelerations of maser lines by tracking their line-of-sight velocities as they change with time. The measured accelerations suggest that the systemic maser spots have a significantly wider radial distribution than in the archetypal megamaser in NGC 4258. We model the maser emission as arising from a circumnuclear disk with orbits dominated by the central black hole. The best fit of the data gives a Hubble constant of H 0 = 68 ± 9 km s –1 Mpc –1 , which corresponds to an angular-diameter distance of 144 ± 19 Mpc. In addition, the fit also gives a mass of the central black hole of (3.09 ± 0.42) × 10 7 M ☉ . The result demonstrates the feasibility of measuring distances to galaxies located well into the Hubble flow by using circumnuclear megamaser disks.

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.

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

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

Angular analysis of $\\Lambda_{b} \\rightarrow \\Lambda \\mu^{+}\\mu^{-}$

CERN Multimedia

Chatzikonstantinidis, Georgios

2018-01-01

The angular analysis of the rare baryon decay of $\\Lambda_{b}\\rightarrow \\Lambda (\\rightarrow p\\pi^{-})\\mu^{+}\\mu^{-}$ in high $q^{2}$ is presented. The dataset that is used corresponds to an integrated luminosity of 5.0 fb$^{-1}$ of pp - collision data collected at centre-of-mass energies between 7 and 13 TeV by the LHCb detector in 2011, 2012, 2015 and 2016. Angular observables are determined using a moment analysis of the angular distribution.

Angular momentum of circularly polarized light in dielectric media

OpenAIRE

Mansuripur, Masud

2014-01-01

A circularly polarized plane-wave is known to have no angular momentum when examined through Maxwell's equations. This, however, contradicts the experimentally observed facts, where finite segments of plane waves are known to be capable of imparting angular momentum to birefringent platelets. Using a superposition of four plane-waves propagating at slightly different angles to a common direction, we derive an expression for the angular momentum density of a single plane-wave in the limit when...

Angular momentum of circularly polarized light in dielectric media

Science.gov (United States)

Mansuripur, Masud

2005-07-01

A circularly polarized plane-wave is known to have no angular momentum when examined through Maxwell’s equations. This, however, contradicts the experimentally observed facts, where finite segments of plane waves are known to be capable of imparting angular momentum to birefringent platelets. Using a superposition of four plane-waves propagating at slightly different angles to a common direction, we derive an expression for the angular momentum density of a single plane-wave in the limit when the propagation directions of the four beams come into alignment. We proceed to use this four-beam technique to analyze the conservation of angular momentum when a plane-wave enters a dielectric slab from the free space. The angular momentum of the beam is shown to decrease upon entering the dielectric medium, by virtue of the fact that the incident beam exerts a torque on the slab surface at the point of entry. When the beam leaves the slab, it imparts an equal but opposite torque to the exit facet, thus recovering its initial angular momentum upon re-emerging into the free-space. Along the way, we derive an expression for the outward-directed force of a normally incident, finite-diameter beam on a dielectric surface; the possible relationship between this force and the experimentally observed bulging of a liquid surface under intense illumination is explored.

Angular momentum conservation law in light-front quantum field theory

Energy Technology Data Exchange (ETDEWEB)

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.; /SLAC /Stanford U.

2017-03-01

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3 , the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QED and QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.

Sorting and quantifying orbital angular momentum of laser beams

CSIR Research Space (South Africa)

Schulze, C

2013-10-01

Full Text Available We present a novel tool for sorting the orbital angular momentum and to determine the orbital angular momentum density of laser beams, which is based on the use of correlation filters....

The mass and angular momentum of reconstructed metric perturbations

Science.gov (United States)

van de Meent, Maarten

2017-06-01

We prove a key result regarding the mass and angular momentum content of linear vacuum perturbations of the Kerr metric obtained through the formalism developed by Chrzarnowski, Cohen, and Kegeles (CCK). More precisely, we prove that the Abbott-Deser mass and angular momentum integrals of any such perturbation vanish when that perturbation was obtained from a regular Fourier mode of the Hertz potential. As a corollary we obtain a generalization of previous results on the completion of the ‘no string’ radiation gauge metric perturbation generated by a point particle. We find that for any bound orbit around a Kerr black hole, the mass and angular momentum perturbations completing the CCK metric are simply the energy and angular momentum of the particle ‘outside’ the orbit and vanish ‘inside’ the orbit.

High Angular Momentum Rydberg Wave Packets

Science.gov (United States)

Wyker, Brendan

2011-12-01

High angular momentum Rydberg wave packets are studied. Application of carefully tailored electric fields to low angular momentum, high- n (n ˜ 300) Rydberg atoms creates coherent superpositions of Stark states with near extreme values of angular momentum, ℓ. Wave packet components orbit the parent nucleus at rates that depend on their energy, leading to periods of localization and delocalization as the components come into and go out of phase with each other. Monitoring survival probability signals in the presence of position dependent probing leads to observation of characteristic oscillations based on the composition of the wave packet. The discrete nature of electron energy levels is observed through the measurement of quantum revivals in the wave packet localization signal. Time-domain spectroscopy of these signals allows determination of both the population and phase of individual superposition components. Precise manipulation of wave packets is achieved through further application of pulsed electric fields. Decoherence effects due to background gas collisions and electrical noise are also detailed. Quantized classical trajectory Monte-Carlo simulations are introduced and agree remarkably well with experimental results.

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

A systematic construction of microstate geometries with low angular momentum

Science.gov (United States)

Bena, Iosif; Heidmann, Pierre; Ramírez, Pedro F.

2017-10-01

We outline a systematic procedure to obtain horizonless microstate geometries that have the same charges as three-charge five-dimensional black holes with a macroscopically-large horizon area and an arbitrarily-small angular momentum. There are two routes through which such solutions can be constructed: using multi-center Gibbons-Hawking (GH) spaces or using superstratum technology. So far the only solutions corre-sponding to microstate geometries for black holes with no angular momentum have been obtained via superstrata [1], and multi-center Gibbons-Hawking spaces have been believed to give rise only to microstate geometries of BMPV black holes with a large angular mo-mentum [2]. We perform a thorough search throughout the parameter space of smooth horizonless solutions with four GH centers and find that these have an angular momentum that is generally larger than 80% of the cosmic censorship bound. However, we find that solutions with three GH centers and one supertube (which are smooth in six-dimensional supergravity) can have an arbitrarily-low angular momentum. Our construction thus gives a recipe to build large classes of microstate geometries for zero-angular-momentum black holes without resorting to superstratum technology.

Effect of nutritional intake towards Angular cheilitis of orphanage children

Directory of Open Access Journals (Sweden)

Nurdiani Rakhmayanthie

2016-11-01

Full Text Available Introduction: Angular cheilitis is one of the oral manifestations of iron, vitamin B12, and folate deficiency. This manifestation frequently seen in people at first and second decade. The purpose of this study was to obtain the prevalence of angular cheilitis and its classifications related to the nutritional intake level in 6-18 years old children. Methods: This research was a descriptive study with 53 children between 6-18 years old from Muhammadiyah Orphanage Bandung as the samples. The oral cavity was examined clinically and their food consumption in a week was noted in Food Recall 24 hours and Food Frequency Questionnaire (FFQ in order to measure their nutritional intake level. Results: There are 23 children with angular cheilitis. 13% has iron and folate deficiencies, and 87% has iron, vitamin B12, and folate deficiencies. Angular cheilitis types that has been found are Type I (39%, Type II (48% and Type III (13%. Conclusion: The prevalence of angular cheilitis in 6-18 years old children in Muhammadiyah Orphanage Bandung was moderately high, most of them were having iron, vitamin B12, and folate deficiencies. Type II angular cheilitis was the most frequently seen.

Velocity distribution of liquid in rotary cylinder when a rotary disc is disposed in contact with a liquid surface; Ekimen ni kaitenenban no arubaai no kaiten entonai ekitai no sokudo bunpu

Energy Technology Data Exchange (ETDEWEB)

Karino, Fumimaru; Kawai, Kazuho; Domoto, Takuya; Takahashi, Toru [Kyoto University, Tokyoto (Japan)

1999-02-05

As a model of a flow in a crucible of Cz method, which is a crystal growth method, a system was formed by flowing water into a rotary cylindrical container and disposing a rotary disc in contact with a free surface of the liquid, and this system was used to determine the velocity distribution in the cylindrical container by a laser Doppler hydrometer. The effects of cylinder rotation Reynolds number, disc rotation Reynolds number, the distance between the disc and the cylinder bottom, and the radius ratio of the disc to the cylinder on the determined radial distribution of tangential time average velocity were examined. As a result, it was found that, in the cases where only the cylinder is rotated, where only the disc is rotated, and where an absolute value of the rotation angular velocity ratio of the disc to the cylinder is small when the cylinder and the disc are rotated in directions inverse to each other, the radial distribution of the time average tangential velocity shows a distribution substantially the same independent on vertical positions, thus Taylor-Proudman theorem is valid. It was further known that, when the disc and the cylinder are rotated in inverse directions and the absolute value of the angular velocity ratio is great, the effect of the disc rotation is remarkable, and particularly, this effect becomes greater in the lower flow than near the disc. (translated by NEDO)

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.

Angular momentum transport with twisted exciton wave packets

Science.gov (United States)

Zang, Xiaoning; Lusk, Mark T.

2017-10-01

A chain of cofacial molecules with CN or CN h symmetry supports excitonic states with a screwlike structure. These can be quantified with the combination of an axial wave number and an azimuthal winding number. Combinations of these states can be used to construct excitonic wave packets that spiral down the chain with well-determined linear and angular momenta. These twisted exciton wave packets can be created and annihilated using laser pulses, and their angular momentum can be optically modified during transit. This allows for the creation of optoexcitonic circuits in which information, encoded in the angular momentum of light, is converted into excitonic wave packets that can be manipulated, transported, and then reemitted. A tight-binding paradigm is used to demonstrate the key ideas. The approach is then extended to quantify the evolution of twisted exciton wave packets in a many-body, multilevel time-domain density functional theory setting. In both settings, numerical methods are developed that allow the site-to-site transfer of angular momentum to be quantified.

Total angular momentum from Dirac eigenspinors

International Nuclear Information System (INIS)

Szabados, Laszlo B

2008-01-01

The eigenvalue problem for Dirac operators, constructed from two connections on the spinor bundle over closed spacelike 2-surfaces, is investigated. A class of divergence-free vector fields, built from the eigenspinors, are found, which, for the lowest eigenvalue, reproduce the rotation Killing vectors of metric spheres, and provide rotation BMS vector fields at future null infinity. This makes it possible to introduce a well-defined, gauge invariant spatial angular momentum at null infinity, which reduces to the standard expression in stationary spacetimes. The general formula for the angular momentum flux carried away by the gravitational radiation is also derived

The H2 + + He proton transfer reaction: quantum reactive differential cross sections to be linked with future velocity mapping experiments

Science.gov (United States)

Hernández Vera, Mario; Wester, Roland; Gianturco, Francesco Antonio

2018-01-01

We construct the velocity map images of the proton transfer reaction between helium and molecular hydrogen ion {{{H}}}2+. We perform simulations of imaging experiments at one representative total collision energy taking into account the inherent aberrations of the velocity mapping in order to explore the feasibility of direct comparisons between theory and future experiments planned in our laboratory. The asymptotic angular distributions of the fragments in a 3D velocity space is determined from the quantum state-to-state differential reactive cross sections and reaction probabilities which are computed by using the time-independent coupled channel hyperspherical coordinate method. The calculations employ an earlier ab initio potential energy surface computed at the FCI/cc-pVQZ level of theory. The present simulations indicate that the planned experiments would be selective enough to differentiate between product distributions resulting from different initial internal states of the reactants.

Investigation of angular and axial smoothing of PET data

International Nuclear Information System (INIS)

Daube-Witherspoon, M.E.; Carson, R.E.

1996-01-01

Radial filtering of emission and transmission data is routinely performed in PET during reconstruction in order to reduce image noise. Angular smoothing is not typically done, due to the introduction of a non-uniform resolution loss; axial filtering is also not usually performed on data acquired in 2D mode. The goal of this paper was to assess the effects of angular and axial smoothing on noise and resolution. Angular and axial smoothing was incorporated into the reconstruction process on the Scanditronix PC2048-15B brain PET scanner. In-plane spatial resolution and noise reduction were measured for different amounts of radial and angular smoothing. For radial positions away from the center of the scanner, noise reduction and degraded tangential resolution with no loss of radial resolution were seen. Near the center, no resolution loss was observed, but there was also no reduction in noise for angular filters up to a 7 degrees FWHM. These results can be understood by considering the combined effects of smoothing projections across rows (angles) and then summing (backprojecting). Thus, angular smoothing is not optimal due to its anisotropic noise reduction and resolution degradation properties. However, uniform noise reduction comparable to that seen with radial filtering can be achieved with axial smoothing of transmission data. The axial results suggest that combined radial and axial transmission smoothing could lead to improved noise characteristics with more isotropic resolution degradation

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.

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.

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

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...

Schmidt decomposition for non-collinear biphoton angular wave functions

International Nuclear Information System (INIS)

Fedorov, M V

2015-01-01

Schmidt modes of non-collinear biphoton angular wave functions are found analytically. The experimentally realizable procedure for their separation is described. Parameters of the Schmidt decomposition are used to evaluate the degree of the biphoton's angular entanglement. (paper)

Modeling of the angular dependence of plasma etching

International Nuclear Information System (INIS)

Guo Wei; Sawin, Herbert H.

2009-01-01

An understanding of the angular dependence of etching yield is essential to investigate the origins of sidewall roughness during plasma etching. In this article the angular dependence of polysilicon etching in Cl 2 plasma was modeled as a combination of individual angular-dependent etching yields for ion-initiated processes including physical sputtering, ion-induced etching, vacancy generation, and removal. The modeled etching yield exhibited a maximum at ∼60 degree sign off-normal ion angle at low flux ratio, indicative of physical sputtering. It transformed to the angular dependence of ion-induced etching with the increase in the neutral-to-ion flux ratio. Good agreement between the modeling and the experiments was achieved for various flux ratios and ion energies. The variation of etching yield in response to the ion angle was incorporated in the three-dimensional profile simulation and qualitative agreement was obtained. The surface composition was calculated and compared to x-ray photoelectron spectroscopy (XPS) analysis. The modeling indicated a Cl areal density of 3x10 15 atoms/cm 2 on the surface that is close to the value determined by the XPS analysis. The response of Cl fraction to ion energy and flux ratio was modeled and correlated with the etching yields. The complete mixing-layer kinetics model with the angular dependence effect will be used for quantitative surface roughening analysis using a profile simulator in future work.

Twisted molecular excitons as mediators for changing the angular momentum of light

Science.gov (United States)

Zang, Xiaoning; Lusk, Mark T.

2017-07-01

Molecules with CN or CN h symmetry can absorb quanta of optical angular momentum to generate twisted excitons with well-defined quasiangular momenta of their own. Angular momentum is conserved in such interactions at the level of a paraxial approximation for the light beam. A sequence of absorption events can thus be used to create a range of excitonic angular momenta. Subsequent decay can produce radiation with a single angular momentum equal to that accumulated. Such molecules can thus be viewed as mediators for changing the angular momentum of light. This sidesteps the need to exploit nonlinear light-matter interactions based on higher-order susceptibilities. A tight-binding paradigm is used to verify angular momentum conservation and demonstrate how it can be exploited to change the angular momentum of light. The approach is then extended to a time-dependent density functional theory setting where the key results are shown to hold in a many-body, multilevel setting.

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.

Approximate method for solving the velocity dependent transport equation in a slab lattice

International Nuclear Information System (INIS)

Ferrari, A.

1966-01-01

A method is described that is intended to provide an approximate solution of the transport equation in a medium simulating a water-moderated plate filled reactor core. This medium is constituted by a periodic array of water channels and absorbing plates. The velocity dependent transport equation in slab geometry is included. The computation is performed in a water channel: the absorbing plates are accounted for by the boundary conditions. The scattering of neutrons in water is assumed isotropic, which allows the use of a double Pn approximation to deal with the angular dependence. This method is able to represent the discontinuity of the angular distribution at the channel boundary. The set of equations thus obtained is dependent only on x and v and the coefficients are independent on x. This solution suggests to try solutions involving Legendre polynomials. This scheme leads to a set of equations v dependent only. To obtain an explicit solution, a thermalization model must now be chosen. Using the secondary model of Cadilhac a solution of this set is easy to get. The numerical computations were performed with a particular secondary model, the well-known model of Wigner and Wilkins. (author) [fr

Angular distributions of ions channeled in the Si crystals

International Nuclear Information System (INIS)

Petrovic, S.; Korica, S.; Kokkoris, M.; Neskovic, N.

2002-01-01

In this study we analyze the angular distributions of Ne 10+ ions channeled in the Si crystals. The ion energy is 60 MeV and the crystal thickness is varied from 286 to 3435 nm. This thickness range corresponds to the reduced crystal thickness range from 0.5 to 6, i.e. from the second to the twelfth rainbow cycle. The angular distributions were obtained via the numerical solution of the ion equations of motion and the computer simulation method. The analysis shows that the angular distribution has a periodic behavior. We also analyze the transmission patterns corresponding to the angular distributions. These patterns should be compared to the experimental patterns obtainable by a two-dimensional position sensitive detector. We demonstrate that, when the ion beam divergence is sufficiently large, i.e. much larger than the critical angle for channeling, the channeling star effect occurs in the transmission patterns

Reexamination of fission fragment angular distributions and the fission process: Formalism

International Nuclear Information System (INIS)

Bond, P.D.

1985-01-01

The theory of fission fragment angular distributions is examined and the universally used expression is found to be valid only under restrictive assumptions. A more general angular distribution formula is derived and applied to recent data of high spin systems. At the same time it is shown that the strong anisotropies observed from such systems can be understood without changing the essential basis of standard fission theory. The effects of reaction mechanisms other than complete fusion on fission fragment angular distributions are discussed and possible angular distribution signatures of noncompound nucleus formation are mentioned

Gravitomagnetism and angular momenta of black-holes

OpenAIRE

Marcelo Samuel Berman

2007-01-01

We review the energy contents formulae of Kerr-Newman black-holes, where gravitomagnetic energy term comes into play (Berman 2004, 2006a,b). Then, we obtain the angular momenta formulae, which include the gravitomagnetic effect. Three theorems can be enunciated: (1) No black-hole has its energy confined to its interior; (2) Rotating black-holes do not have confined angular momenta; (3) The energy density of a black-hole is not confined to its interior. The difference between our calculation a...

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.

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)

Remote determination of the velocity index and mean streamwise velocity profiles

Science.gov (United States)

Johnson, E. D.; Cowen, E. A.

2017-09-01

When determining volumetric discharge from surface measurements of currents in a river or open channel, the velocity index is typically used to convert surface velocities to depth-averaged velocities. The velocity index is given by, k=Ub/Usurf, where Ub is the depth-averaged velocity and Usurf is the local surface velocity. The USGS (United States Geological Survey) standard value for this coefficient, k = 0.85, was determined from a series of laboratory experiments and has been widely used in the field and in laboratory measurements of volumetric discharge despite evidence that the velocity index is site-specific. Numerous studies have documented that the velocity index varies with Reynolds number, flow depth, and relative bed roughness and with the presence of secondary flows. A remote method of determining depth-averaged velocity and hence the velocity index is developed here. The technique leverages the findings of Johnson and Cowen (2017) and permits remote determination of the velocity power-law exponent thereby, enabling remote prediction of the vertical structure of the mean streamwise velocity, the depth-averaged velocity, and the velocity index.

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.)

The INCAS Project: An Innovative Contact-Less Angular Sensor

Science.gov (United States)

Ghislanzoni, L.; Di Cintio, A.; Solimando, M.; Parzianello, G.

2013-09-01

Angular Positions sensors are widely used in all spacecrafts, including re-entry vehicles and launchers, where mechanisms and pointing-scanning devices are required. The main applications are on mechanisms for TeleMeasure (TM) related to the release and deployment of devices, or on rotary mechanisms such as Solar Array Drive Mechanism (SADM) and Antenna Pointing Mechanism (APM). Longer lifetime (up to 7- 10 years) is becoming a new driver for the coming missions and contact technology sensors often incur in limitations due to the wear of the contacting parts [1].A Self-Compensating Absolute Angular Encoder was developed and tested in the frame of an ESA's ARTES 5.2 project, named INCAS (INnovative Contact-less Angular Sensor). More in particular, the INCAS sensor addresses a market need for contactless angular sensors aimed at replacing the more conventional rotary potentiometers, while featuring the same level of accuracy performances and extending the expected lifetime.

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%.

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.

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

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.

AngularJS in the Wild: A Survey with 460 Developers

OpenAIRE

Ramos, Miguel; Valente, Marco Tulio; Terra, Ricardo; Santos, Gustavo

2016-01-01

To implement modern web applications, a new family of JavaScript frameworks has emerged, using the MVC pattern. Among these frameworks, the most popular one is AngularJS, which is supported by Google. In spite of its popularity, there is not a clear knowledge on how AngularJS design and features affect the development experience of Web applications. Therefore, this paper reports the results of a survey about AngularJS, including answers from 460 developers. Our contributions include the ident...

Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

Science.gov (United States)

Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

2016-04-01

We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.

Studying AGN Jets At Extreme Angular Resolution

Science.gov (United States)

Bruni, Gabriele

2016-10-01

RadioAstron is a 10m antenna orbiting on the Russian Speckt-R spacecraft, launched in 2011. Performing radio interferometry with a global array of ground telescopes, it is providing record angular resolution. The Key Science Project on AGN polarization is exploiting it to study in great detail the configuration of magnetic fields in AGN jets, and understand their formation and collimation. To date, the project has already achieved the highest angular resolution image ever obtained in Astronomy, and detected brightness temperatures exceeding the ones predicted by theory of AGN.

Interpreting angular momentum transfer between electromagnetic multipoles using vector spherical harmonics.

Science.gov (United States)

Grinter, Roger; Jones, Garth A

2018-02-01

The transfer of angular momentum between a quadrupole emitter and a dipole acceptor is investigated theoretically. Vector spherical harmonics are used to describe the angular part of the field of the mediating photon. Analytical results are presented for predicting angular momentum transfer between the emitter and absorber within a quantum electrodynamical framework. We interpret the allowability of such a process, which appears to violate conservation of angular momentum, in terms of the breakdown of the isotropy of space at the point of photon absorption (detection). That is, collapse of the wavefunction results in loss of all angular momentum information. This is consistent with Noether's Theorem and demystifies some common misconceptions about the nature of the photon. The results have implications for interpreting the detection of photons from multipole sources and offers insight into limits on information that can be extracted from quantum measurements in photonic systems.

Processing of angular motion and gravity information through an internal model.

Science.gov (United States)

Laurens, Jean; Straumann, Dominik; Hess, Bernhard J M

2010-09-01

The vestibular organs in the base of the skull provide important information about head orientation and motion in space. Previous studies have suggested that both angular velocity information from the semicircular canals and information about head orientation and translation from the otolith organs are centrally processed in an internal model of head motion, using the principles of optimal estimation. This concept has been successfully applied to model behavioral responses to classical vestibular motion paradigms. This study measured the dynamic of the vestibuloocular reflex during postrotatory tilt, tilt during the optokinetic afternystagmus, and off-vertical axis rotation. The influence of otolith signal on the VOR was systematically varied by using a series of tilt angles. We found that the time constants of responses varied almost identically as a function of gravity in these paradigms. We show that Bayesian modeling could predict the experimental results in an accurate and consistent manner. In contrast to other approaches, the Bayesian model also provides a plausible explanation of why these vestibulooculo motor responses occur as a consequence of an internal process of optimal motion estimation.

Positron annihilation and perturbed angular correlation studies of radiation damage

International Nuclear Information System (INIS)

Zhu Jiazheng; Li Anli; Xu Yongjun; Wang Zhiqiang; Zhou Dongmei; Zheng Yongnan; Zhu Shengyun; Iwata, T.

2002-01-01

The positron annihilation and perturbed angular correlation techniques have been employed to study radiation damage in Si and Nb. The results obtained by the positron annihilation are consistent with those given by the perturbed angular correlation

Analysis of angular momentum properties of photons emitted in fundamental atomic processes

Science.gov (United States)

Zaytsev, V. A.; Surzhykov, A. S.; Shabaev, V. M.; Stöhlker, Th.

2018-04-01

Many atomic processes result in the emission of photons. Analysis of the properties of emitted photons, such as energy and angular distribution as well as polarization, is regarded as a powerful tool for gaining more insight into the physics of corresponding processes. Another characteristic of light is the projection of its angular momentum upon propagation direction. This property has attracted a special attention over the past decades due to studies of twisted (or vortex) light beams. Measurements being sensitive to this projection may provide valuable information about the role of angular momentum in the fundamental atomic processes. Here we describe a simple theoretical method for determination of the angular momentum properties of the photons emitted in various atomic processes. This method is based on the evaluation of expectation value of the total angular momentum projection operator. To illustrate the method, we apply it to the textbook examples of plane-wave, spherical-wave, and Bessel light. Moreover, we investigate the projection of angular momentum for the photons emitted in the process of the radiative recombination with ionic targets. It is found that the recombination photons do carry a nonzero projection of the orbital angular momentum.

Perturbed angular correlation

International Nuclear Information System (INIS)

Fabris, J.D.

1977-01-01

The electric quadrupolar interaction in some hafnium complexes, measured at the metal nucleus level is studied. For that purpose, the technique of γ-γ perturbed angular correlation is used: the frequencies of quadrupolar interaction are compared with some hafnium α-hydroxicarboxilates, namely glycolate, lactate, mandelate and benzylate; the influence of the temperature on the quadrupolar coupling on the hafnium tetramandelate is studied; finally, the effects associated with the capture of thermal neutrons by hafnium tetramandelate are examined locally at the nuclear level. The first group of results shows significant differences in a series of complexes derived from glycolic acid. On the other hand, the substitution of the protons in hafnium tetramandelate structure by some alkaline cations permits to verify a correlation between the variations in the quadrupolar coupling and the electronegativities of the substituent elements. Measurements at high temperatures show that this complex is thermally stable at 100 and 150 0 C. It is possible to see the appearance of two distinct sites for the probe nucleus, after heating the sample at 100 0 C for prolonged time. This fact is attributed to a probable interconversion among the postulated structural isomers for the octacoordinated compounds. Finally, measurements of angular correlation on the irradiated complex show that there is an effective destruction of the target molecule by neutron capture [pt

Development of an optimal velocity selection method with velocity obstacle

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Geuk; Oh, Jun Ho [KAIST, Daejeon (Korea, Republic of)

2015-08-15

The Velocity obstacle (VO) method is one of the most well-known methods for local path planning, allowing consideration of dynamic obstacles and unexpected obstacles. Typical VO methods separate a velocity map into a collision area and a collision-free area. A robot can avoid collisions by selecting its velocity from within the collision-free area. However, if there are numerous obstacles near a robot, the robot will have very few velocity candidates. In this paper, a method for choosing optimal velocity components using the concept of pass-time and vertical clearance is proposed for the efficient movement of a robot. The pass-time is the time required for a robot to pass by an obstacle. By generating a latticized available velocity map for a robot, each velocity component can be evaluated using a cost function that considers the pass-time and other aspects. From the output of the cost function, even a velocity component that will cause a collision in the future can be chosen as a final velocity if the pass-time is sufficiently long enough.

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.

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

Solution of neutron transport equation using Daubechies' wavelet expansion in the angular discretization

International Nuclear Information System (INIS)

Cao Liangzhi; Wu Hongchun; Zheng Youqi

2008-01-01

Daubechies' wavelet expansion is introduced to discretize the angular variables of the neutron transport equation when the neutron angular flux varies very acutely with the angular directions. An improvement is made by coupling one-dimensional wavelet expansion and discrete ordinate method to make two-dimensional angular discretization efficient and stable. The angular domain is divided into several subdomains for treating the vacuum boundary condition exactly in the unstructured geometry. A set of wavelet equations coupled with each other is obtained in each subdomain. An iterative method is utilized to decouple the wavelet moments. The numerical results of several benchmark problems demonstrate that the wavelet expansion method can provide more accurate results by lower-order expansion than other angular discretization methods

Velocity map imaging of ion-molecule reaction products: Co+(3F4)+isobutane

Science.gov (United States)

Reichert, Emily L.; Thurau, Gert; Weisshaar, James C.

2002-07-01

The velocity map imaging technique is applied to mass-selected CoC3H6++CH4 and CoC4H8++H2 elimination products from the Co+(3F4)+isobutane reaction studied under crossed-beam conditions at 0.21 eV collision energy. For both reactions we obtain the joint scattering probability distribution P(E,Θ), where E and Θ are the product translational energy and scattering angle. The fraction of available energy deposited into product translation is 0.4 for H2, compared with 0.1 for CH4. For the CH4 product, the angular distribution is forward-backwards symmetric and sharply peaked at Θ=0 and 180°. P(E,Θ) is not separable into the product of an energy and an angular function; rather, the angular distribution peaks more sharply at higher translational energy. Evidently, incipient CoC3H6++CH4 products equilibrate in the Co+(C3H6)(CH4) exit-channel well, from which they decay statistically. The product translational energy distribution P(E) is consistent with orbiting-transition state phase-space theory with no exit-channel barrier. In addition, the energy-integrated angular distribution T(Θ) is consistent with the predictions of the early statistical complex decay model of Miller and Herschbach for fragmentation from a transition state that is a prolate top. In sharp contrast, P(E) for the CoC4H8++H2 products exhibits a substantial hot, nonstatistical tail towards high energy. Perhaps the H2 channel has a late potential energy barrier some 0.5 eV above products, but we view this explanation as highly unlikely. Instead, we suggest that the potential energy from an earlier multicenter transition state is funneled efficiently, and highly nonstatistically, into product translation. This surprising conclusion may apply to H2 products for the entire family of reactions of the late-3D series transition metal cations Fe+, Co+, and Ni+ with alkanes.

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.

Angular dependence of Auger signals from a GaAs (111) surface

International Nuclear Information System (INIS)

Barnard, W.O.

1984-03-01

This dissertation is concerned with the angular dependence of the L 3 M 4 M 4 1067 eV Ga and L 3 M 4 M 4 1228 eV As Auger electron signals from a (111) GaAs surface, using a system which is equipped with a cylindrical mirror analyser. Following a detailed discussion of the Auger process, a review is given of angular effects in the emission excitation and detection of Auger signals. Present theories are discussed and an empirical theory is developed to test the experimental results obtained in this study. The experimental procedures and equipment used are presented. It was found that the Auger signals show a strong variation with the angle of rotation about the normal of a GaAs surface. Furthermore, the nature of the angular spectra of the Ga and As signals are interchanged when the electron beam incident surface is changed from (111) to (111). The main features of the angular variation of the quasi-elastic backscattered signal is reflected in the corresponding Ga and As Auger angular spectra. The angular dependence of the quasi-elastic backscattered signal can be explained semi-quantitatively in terms of the empirical theory. Theoretical arguments are presented which suggest that the Auger signals should show an angular dependence similar to the quasi-elastic backscattered signal. Evidence was found that geometric screening-off of underlying atoms by surface and near surface atoms influence the Auger yield

Depth of origin and angular spectrum of sputtered atoms

International Nuclear Information System (INIS)

Vicanek, M.; Jimenez Rodriguez, J.J.; Sigmund, P.

1989-01-01

A theoretical analysis is presented of the depth of origin of atoms sputtered from a random target. The physical model aims at high energy sputtering under linear cascade conditions and assumes a dilute source of recoil atoms. The initial distribution of the recoils is assumed isotropic, and their energy distribution is E -2 like without an upper or lower cutoff. The scattering medium is either infinite or bounded by a plane surface. Atoms scatter according to the m=0 power cross section. Electronic stopping is ignored. The sputtered flux, differential in depth of origin, ejection energy and ejection angle has been evaluated by Monte Carlo simulation and by five distinct methods of solution of the linear Boltzmann equation reaching from continuous slowing down neglecting angular scattering to the P 3 approximation and a Gram-Charlier expansion going over spatial moments. The continuous slowing down approximation used in previous work leads to results that are identical to those found from a scheme that only ignores angular scattering but allows for energy loss straggling. Moreover, these predictions match more closely with the Monte Carlo results than any of the approximate analytical schemes that take account of angular scattering. The results confirm the common assertion that the depth of origin of sputtered atoms is determined mainly by the stopping of low energy recoil atoms. The effect of angular scattering turns out to be astonishingly small. The distributions in depth of origin, energy, and angle do not depend significantly on whether the scattering medium is a halfspace or an infinite medium with a reference plane. The angular spectrum comes out only very slightly over cosine from the model as it stands, in agreement with previous experience, but comments are made on essential features that are not incorporated in the physical model but might influence the angular spectrum. (orig./WL)

Physics from angular projection of rectangular grids

International Nuclear Information System (INIS)

Singh, Ashmeet

2015-01-01

In this paper, we present a mathematical model for the angular projection of a rectangular arrangement of points in a grid. This simple yet interesting, problem has both scholarly value and applications for data extraction techniques to study the physics of various systems. Our work may help undergraduate students to understand subtle points in the angular projection of a grid and describes various quantities of interest in the projection with completeness and sufficient rigour. We show that for certain angular ranges, the projection has non-distinctness, and calculate the details of such angles, and correspondingly, the number of distinct points and the total projected length. We focus on interesting trends obtained for the projected length of the grid elements and present a simple application of the model to determine the geometry of an unknown grid whose spatial extensions are known, using measurement of the grid projection at two angles only. Towards the end, our model is shown to have potential applications in various branches of physical sciences, including crystallography, astrophysics, and bulk properties of materials. (paper)

Optical Torque Wrench: Angular Trapping, Rotation, and Torque Detection of Quartz Microparticles

Science.gov (United States)

La Porta, Arthur; Wang, Michelle D.

2004-05-01

We describe an apparatus that can measure the instantaneous angular displacement and torque applied to a quartz particle which is angularly trapped. Torque is measured by detecting the change in angular momentum of the transmitted trap beam. The rotational Brownian motion of the trapped particle and its power spectral density are used to determine the angular trap stiffness. The apparatus features a feedback control that clamps torque or other rotational quantities. The torque sensitivity demonstrated is ideal for the study of known biological molecular motors.

Angular distribution of atoms ejected by laser ablation of different metals

International Nuclear Information System (INIS)

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

2009-01-01

Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm 2 ) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos n θ distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.

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

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.

Angular-momentum-dominated electron beams and flat-beam generation

International Nuclear Information System (INIS)

Sun, Yin-e

2005-01-01

In the absence of external forces, if the dynamics within an electron beam is dominated by its angular momentum rather than other effects such as random thermal motion or self Coulomb-repulsive force (i.e., space-charge force), the beam is said to be angular-momentum-dominated. Such a beam can be directly applied to the field of electron-cooling of heavy ions; or it can be manipulated into an electron beam with large transverse emittance ratio, i.e., a flat beam. A flat beam is of interest for high-energy electron-positron colliders or accelerator-based light sources. An angular-momentum-dominated beam is generated at the Fermilab/NICADD photoinjector Laboratory (FNPL) and is accelerated to an energy of 16 MeV. The properties of such a beam is investigated systematically in experiment. The experimental results are in very good agreement with analytical expectations and simulation results. This lays a good foundation for the transformation of an angular-momentum-dominated beam into a flat beam. The round-to-flat beam transformer is composed of three skew quadrupoles. Based on a good knowledge of the angular-momentum-dominated beam, the quadrupoles are set to the proper strengths in order to apply a total torque which removes the angular momentum, resulting in a flat beam. For bunch charge around 0.5 nC, an emittance ratio of 100 ± 5 was measured, with the smaller normalized root-mean-square emittance around 0.4 mm-mrad. Effects limiting the flat-beam emittance ratio are investigated, such as the chromatic effects in the round-to-flat beam transformer, asymmetry in the initial angular-momentum-dominated beam, and space-charge effects. The most important limiting factor turns out to be the uncorrelated emittance growth caused by space charge when the beam energy is low, for example, in the rf gun area. As a result of such emittance growth prior to the round-to-flat beam transformer, the emittance ratio achievable in simulation decreases from orders of thousands to

Angular-momentum-dominated electron beams and flat-beam generation

Energy Technology Data Exchange (ETDEWEB)

Sun, Yin-e [Univ. of Chicago, IL (United States)

2005-06-01

In the absence of external forces, if the dynamics within an electron beam is dominated by its angular momentum rather than other effects such as random thermal motion or self Coulomb-repulsive force (i.e., space-charge force), the beam is said to be angular-momentum-dominated. Such a beam can be directly applied to the field of electron-cooling of heavy ions; or it can be manipulated into an electron beam with large transverse emittance ratio, i.e., a flat beam. A flat beam is of interest for high-energy electron-positron colliders or accelerator-based light sources. An angular-momentum-dominated beam is generated at the Fermilab/NICADD photoinjector Laboratory (FNPL) and is accelerated to an energy of 16 MeV. The properties of such a beam is investigated systematically in experiment. The experimental results are in very good agreement with analytical expectations and simulation results. This lays a good foundation for the transformation of an angular-momentum-dominated beam into a flat beam. The round-to-flat beam transformer is composed of three skew quadrupoles. Based on a good knowledge of the angular-momentum-dominated beam, the quadrupoles are set to the proper strengths in order to apply a total torque which removes the angular momentum, resulting in a flat beam. For bunch charge around 0.5 nC, an emittance ratio of 100 ± 5 was measured, with the smaller normalized root-mean-square emittance around 0.4 mm-mrad. Effects limiting the flat-beam emittance ratio are investigated, such as the chromatic effects in the round-to-flat beam transformer, asymmetry in the initial angular-momentum-dominated beam, and space-charge effects. The most important limiting factor turns out to be the uncorrelated emittance growth caused by space charge when the beam energy is low, for example, in the rf gun area. As a result of such emittance growth prior to the round-to-flat beam transformer, the emittance ratio achievable in simulation decreases from orders of thousands to

New approach to determine the angular transmission in zero-degree magnetic spectrometers

International Nuclear Information System (INIS)

Benlliure, J.; Pereira-Conca, J.; Schmidt, K.H.

2000-11-01

A new method to estimate the angular transmission in zero-degree magnetic spectrometers is presented. This method is based on a parameterisation of the angular aperture of the spectrometer for any possible value of the magnetic rigidity of the transmitted particles. This parameterisation of the angular aperture together with a description of the kinematics of the reaction mechanism allows to determine the angular transmission analytically, avoiding tedious Monte-Carlo calculations. The analytical solutions are implemented for residual nuclei produced in fission, projectile-fragmentation and fusion-evaporation reactions. (orig.)

Quantum entanglement of high angular momenta.

Science.gov (United States)

Fickler, Robert; Lapkiewicz, Radek; Plick, William N; Krenn, Mario; Schaeff, Christoph; Ramelow, Sven; Zeilinger, Anton

2012-11-02

Single photons with helical phase structures may carry a quantized amount of orbital angular momentum (OAM), and their entanglement is important for quantum information science and fundamental tests of quantum theory. Because there is no theoretical upper limit on how many quanta of OAM a single photon can carry, it is possible to create entanglement between two particles with an arbitrarily high difference in quantum number. By transferring polarization entanglement to OAM with an interferometric scheme, we generate and verify entanglement between two photons differing by 600 in quantum number. The only restrictive factors toward higher numbers are current technical limitations. We also experimentally demonstrate that the entanglement of very high OAM can improve the sensitivity of angular resolution in remote sensing.

Factorial correlators: angular scaling within QCD jets

International Nuclear Information System (INIS)

Peschanski, R.

2001-01-01

Factorial correlators measure the amount of dynamical correlation in the multiplicity between two separated phase-space windows. We present the analytical derivation of factorial correlators for a QCD jet described at the double logarithmic (DL) accuracy. We obtain a new angular scaling property for properly normalized correlators between two solid-angle cells or two rings around the jet axis. Normalized QCD factorial correlators scale with the angular distance and are independent of the window size. Scaling violations are expected beyond the DL approximation, in particular from the subject structure. Experimental tests are feasible, and thus would be welcome. (orig.)

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.

Negative refraction angular characterization in one-dimensional photonic crystals.

Science.gov (United States)

Lugo, Jesus Eduardo; Doti, Rafael; Faubert, Jocelyn

2011-04-06

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.

Angular momentum projection with Pfaffian

International Nuclear Information System (INIS)

Oi, M.

2011-01-01

Recent developments to rewrite the Onishi formula for an evaluation of the so-called norm overlap kernel necessary in angular momentum projection are to be discussed. The essential ingredients in the development, that is, the Fermion coherent states, the Grassmann numbers, and the Pfaffian, are explained. (author)

Angular distribution of sputtered atoms from Al-Sn alloy and surface topography

International Nuclear Information System (INIS)

Wang Zhenxia; Pan Jisheng; Zhang Jiping; Tao Zhenlan

1992-01-01

If an alloy is sputtered the angular distribution of the sputtered atoms can be different for each component. At high ion energies in the range of linear cascade theory, different energy distributions for components of different mass in the solid are predicted. Upon leaving the surface, i.e. overcoming the surface binding energy, these differences should show up in different angular distributions. Differences in the angular distribution are of much practical interest, for example, in thin-film deposition by sputtering and surface analysis by secondary-ion mass spectroscopy and Auger electron spectroscopy. Recently our experimental work has shown that for Fe-W alloy the surface microtopography becomes dominant and determines the shape of the angular distribution of the component. However, with the few experimental results available so far it is too early to draw any general conclusions for the angular distribution of the sputtered constituents. Thus, the aim of this work was to study further the influence of the surface topography on the shape of the angular distribution of sputtered atoms from an Al-Sn alloy. (Author)

Isotropic gates in large gamma detector arrays versus angular distributions

International Nuclear Information System (INIS)

Iacob, V.E.; Duchene, G.

1997-01-01

The quality of the angular distribution information extracted from high-fold gamma-gamma coincidence events is analyzed. It is shown that a correct quasi-isotropic gate setting, available at the modern large gamma-ray detector arrays, essentially preserves the quality of the angular information. (orig.)

The dependence of the period on the angular amplitude of a simple ...

African Journals Online (AJOL)

The timing of the oscillation was done as the bob passed through its rest position. The time for 50 oscillations was recorded for different lengths and angular amplitudes. It was observed that the period depends on length and angular amplitude of the pendulum. The variation of the period with the angular amplitude is not a ...

On Angular Sampling Methods for 3-D Spatial Channel Models

DEFF Research Database (Denmark)

Fan, Wei; Jämsä, Tommi; Nielsen, Jesper Ødum

2015-01-01

This paper discusses generating three dimensional (3D) spatial channel models with emphasis on the angular sampling methods. Three angular sampling methods, i.e. modified uniform power sampling, modified uniform angular sampling, and random pairing methods are proposed and investigated in detail....... The random pairing method, which uses only twenty sinusoids in the ray-based model for generating the channels, presents good results if the spatial channel cluster is with a small elevation angle spread. For spatial clusters with large elevation angle spreads, however, the random pairing method would fail...... and the other two methods should be considered....

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;

Galaxy angular momentum

International Nuclear Information System (INIS)

Thompson, L.A.

1974-01-01

In order to test the theories which purport to explain the origin of galaxy angular momentum, this study presents new data for about 1000 individual galaxies in eight rich clusters. The clusters which are studied include Virgo, A 119, A 400, A 1656 (Coma), A 2147, A 2151 (Hercules), A 2197, and A 2199. Selected samples of these data are used to investigate systematic alignment effects in clusters of galaxies and to investigate the intrinsic ellipticities of E, SO, and spiral galaxies. The following new results are reported: Galaxies in the cluster A 2197 show a significant alignment effect (chi 2 probability less than 0.0002), and the preferential direction of alignment corresponds approximately to the major axis of the overall cluster elongation. None of the other seven clusters show any significant alignment trends. The spiral galaxy samples in four clusters (Virgo, A 1656, A 2151, and A 2197) were large enough to analyze the number distributions of forward and reverse winding spirals. Large and small spiral galaxies have identical ellipticity distributions. Large E and SO galaxies tend to be more spherical, and small E and SO galaxies more flattened. The intrinsic ellipticities of E, SO, and spiral galaxies are the same for galaxies in the ''field'' and for galaxies in rich clusters. Six models of galaxy formation are reviewed, and the major []mphasis is placed on how each model explains the origin of galaxy angular momentum. (Diss. Abstr. Int., B)

Information content in B→VV decays and the angular moments method

International Nuclear Information System (INIS)

Dighe, A.; Sen, S.

1998-10-01

The time-dependent angular distributions of decays of neutral B mesons into two vector mesons contain information about the lifetimes, mass differences, strong and weak phases, form factors, and CP violating quantities. A statistical analysis of the information content is performed by giving the ''information'' a quantitative meaning. It is shown that for some parameters of interest, the information content in time and angular measurements combined may be orders of magnitude more than the information from time measurements alone and hence the angular measurements are highly recommended. The method of angular moments is compared with the (maximum) likelihood method to find that it works almost as well in the region of interest for the one-angle distribution. For the complete three-angle distribution, an estimate of possible statistical errors expected on the observables of interest is obtained. It indicates that the three-angle distribution, unraveled by the method of angular moments, would be able to nail down many quantities of interest and will help in pointing unambiguously to new physics. (author)

Biomechanical considerations of distance kicking in Australian Rules football.

Science.gov (United States)

Ball, Kevin

2008-01-01

Kicking for distance in Australian Rules football is an important skill. Here, I examine technical aspects that contribute to achieving maximal kick distance. Twenty-eight elite players kicked for distance while being videoed at 500 Hz. Two-dimensional digitized data of nine body landmarks and the football were used to calculate kinematic parameters from kicking foot toe-off to the instant before ball contact. Longer kick distances were associated with greater foot speeds and shank angular velocities at ball contact, larger last step lengths, and greater distances from the ground when ball contact occurred. Foot speed, shank angular velocity, and ball position relative to the support foot at ball contact were included in the best regression predicting distance. A continuum of technique was evident among the kickers. At one end, kickers displayed relatively larger knee angular velocities and smaller thigh angular velocities at ball contact. At the other end, kickers produced relatively larger thigh angular velocities and smaller knee angular velocities at ball contact. To increase kicking distance, increasing foot speed and shank angular velocity at ball contact, increasing the last step length, and optimizing ball position relative to the ground and support foot are recommended.

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.

Operator theory of angular momentum nad orientational auto-correlation functions

International Nuclear Information System (INIS)

Evans, M.W.

1982-01-01

The rigorous relation between the orientational auto-correlation function and the angular momentum autocorrelation function is described in two cases of interest. First when description of the complete zero THz- spectrum is required from the Mori continued fraction expansion for the angular momentum autocorrelation function and second when rotation/translation effects are important. The Mori-Evans theory of 1976, relying on the simple Shimizu relation is found to be essentially unaffected by the higher order corrections recently worked out by Ford and co-workers in the Markov limit. The mutual interaction of rotation and translation is important in determining the details of both the orientational and angular momentum auto-correlation function's (a.c.f.'s) in the presence of sample anisotropy or a symmetry breaking field. In this case it is essential to regard the angular momentum a.c.f. as non-Markovian and methods are developed to relate this to the orientational a.c.f. in the presence of rotation/translation coupling. (author)

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.

Chirality and angular momentum in optical radiation

Science.gov (United States)

Coles, Matt M.; Andrews, David L.

2012-06-01

This paper develops, in precise quantum electrodynamic terms, photonic attributes of the “optical chirality density,” one of several measures long known to be conserved quantities for a vacuum electromagnetic field. The analysis lends insights into some recent interpretations of chiroptical experiments, in which this measure, and an associated chirality flux, have been treated as representing physically distinctive “superchiral” phenomena. In the fully quantized formalism the chirality density is promoted to operator status, whose exploration with reference to an arbitrary polarization basis reveals relationships to optical angular momentum and helicity operators. Analyzing multimode beams with complex wave-front structures, notably Laguerre-Gaussian modes, affords a deeper understanding of the interplay between optical chirality and optical angular momentum. By developing theory with due cognizance of the photonic character of light, it emerges that only the spin-angular momentum of light is engaged in such observations. Furthermore, it is shown that these prominent measures of the helicity of chiral electromagnetic radiation have a common basis in differences between the populations of optical modes associated with angular momenta of opposite sign. Using a calculation of the rate of circular dichroism as an example, with coherent states to model the electromagnetic field, it is discovered that two terms contribute to the differential effect. The primary contribution relates to the difference in left- and right-handed photon populations; the only other contribution, which displays a sinusoidal distance dependence corresponding to the claim of nodal enhancements, is connected with the quantum photon number-phase uncertainty relation. From the full analysis, it appears that the term “superchiral” can be considered redundant.

Simulation and experimental studies of a double-fiber angular displacement sensor

Science.gov (United States)

Zhu, Ruixue; Jing, Ruiping; Cheng, Yongjin

2017-03-01

A novel optical fiber angular displacement sensor is reported in this study. It gets the rotating angle of an object by means of the intensity modulation of a reflected light. The sensor probe, which is composed of an emitting fiber and a receiving fiber that are aligned along the vertical direction closely, is fixed directly on the rotating object. The measurements for axial displacement and angular displacement were operated separately. In particular, measurements for angular displacement were performed when the reflector is placed at different distances from the sensor probe separately. There is an excellent linearity between the angular displacement and the sensor output power. The results indicate that the larger the distance between the sensor probe and the reflector, the higher sensitivity the angular displacement sensor has. A theoretical model of the sensor is also developed and the simulate computation demonstrates that the theoretical results are in accordance with the experimental ones. The linear sensing range is ±7.2°, and the maximum sensitivity is 13.71%/deg. Furthermore, the hysteresis and the reproducibility of the measurement of the sensor are investigated. The designed sensor provides a kind of simple and effective method for measuring the angular displacement of a shaft system in practice due to its small size, light weight, good linearity and reproducibility.

Prediction of Lunar Reconnaissance Orbiter Reaction Wheel Assembly Angular Momentum Using Regression Analysis

Science.gov (United States)

DeHart, Russell

2017-01-01

This study determines the feasibility of creating a tool that can accurately predict Lunar Reconnaissance Orbiter (LRO) reaction wheel assembly (RWA) angular momentum, weeks or even months into the future. LRO is a three-axis stabilized spacecraft that was launched on June 18, 2009. While typically nadir-pointing, LRO conducts many types of slews to enable novel science collection. Momentum unloads have historically been performed approximately once every two weeks with the goal of maintaining system total angular momentum below 70 Nms; however flight experience shows the models developed before launch are overly conservative, with many momentum unloads being performed before system angular momentum surpasses 50 Nms. A more accurate model of RWA angular momentum growth would improve momentum unload scheduling and decrease the frequency of these unloads. Since some LRO instruments must be deactivated during momentum unloads and in the case of one instrument, decontaminated for 24 hours there after a decrease in the frequency of unloads increases science collection. This study develops a new model to predict LRO RWA angular momentum. Regression analysis of data from October 2014 to October 2015 was used to develop relationships between solar beta angle, slew specifications, and RWA angular momentum growth. The resulting model predicts RWA angular momentum using input solar beta angle and mission schedule data. This model was used to predict RWA angular momentum from October 2013 to October 2014. Predictions agree well with telemetry; of the 23 momentum unloads performed from October 2013 to October 2014, the mean and median magnitude of the RWA total angular momentum prediction error at the time of the momentum unloads were 3.7 and 2.7 Nms, respectively. The magnitude of the largest RWA total angular momentum prediction error was 10.6 Nms. Development of a tool that uses the models presented herein is currently underway.

Effect of Coulomb friction on orientational correlation and velocity distribution functions in a sheared dilute granular gas.

Science.gov (United States)

Gayen, Bishakhdatta; Alam, Meheboob

2011-08-01

From particle simulations of a sheared frictional granular gas, we show that the Coulomb friction can have dramatic effects on orientational correlation as well as on both the translational and angular velocity distribution functions even in the Boltzmann (dilute) limit. The dependence of orientational correlation on friction coefficient (μ) is found to be nonmonotonic, and the Coulomb friction plays a dual role of enhancing or diminishing the orientational correlation, depending on the value of the tangential restitution coefficient (which characterizes the roughness of particles). From the sticking limit (i.e., with no sliding contact) of rough particles, decreasing the Coulomb friction is found to reduce the density and spatial velocity correlations which, together with diminished orientational correlation for small enough μ, are responsible for the transition from non-gaussian to gaussian distribution functions in the double limit of small friction (μ→0) and nearly elastic particles (e→1). This double limit in fact corresponds to perfectly smooth particles, and hence the maxwellian (gaussian) is indeed a solution of the Boltzmann equation for a frictional granular gas in the limit of elastic collisions and zero Coulomb friction at any roughness. The high-velocity tails of both distribution functions seem to follow stretched exponentials even in the presence of Coulomb friction, and the related velocity exponents deviate strongly from a gaussian with increasing friction.

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

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.

Angular dependence of spin-orbit spin-transfer torques

KAUST Repository

Lee, Ki-Seung; Go, Dongwook; Manchon, Aurelien; Haney, Paul M.; Stiles, M. D.; Lee, Hyun-Woo; Lee, Kyung-Jin

2015-01-01

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.

Comparison of experimental and calculated neutron emission spectra and angular distributions

International Nuclear Information System (INIS)

Gruppelaar, H.; Akkermans, J.M.

1980-06-01

Experimental and calculated neutron emission spectra and angular distributions have been intercompared for 14.6-MeV neutron-induced reactions. The experimental data, measured by Hermsdorf et al., cover 34 elements in a large mass range. To calculate the differential neutron scattering cross sections a unified model of preequilibrium neutron emission was used, in which the generalized master equation of Mantzouranis et al. was solved with a fast exact matrix method, recently introduced by Akkermans. For the scattering kernel a three-term Legendre polynomial representation was adopted, which was either derived from the differential free nucleon-nucleon scattering cross section or fitted to obtain optimal agreement with the set of experimental data of Hermsdorf et al. The results of the last-mentioned calculation are quite acceptable in view of the fact that only two global parameters have been to describe the angular distributions of all experimental data. The report contains tables and graphs of the calculated Legendre coefficients and graphs of energy-averaged angular distributions for all 34 elements. It is further shown that improvements in the energy and angular distributions could be obtained by means of adjustment of the level-density parameters of the individual residual nuclei. Finally a short discussion is devoted to the problems of fitting angular distributions at backward angles by varying the model parameters or the specification of the initial condition. It is indicated that the so-called preequilibrium phase of the nuclear reaction actually consists of two different stages, the first one generating the forward-peaked angular distributions and the second one showing angular distributions symmetric about 90 0

Relationship between lower limbs kinematic variables and effectiveness of sprint during maximum velocity phase.

Science.gov (United States)

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

2015-01-01

The aim of the study was to determine the relationships between time of running over a 15-25 m section of a 30-meter run along a straight line and changes in the angle and angular velocity observed in ankle, knee and hip joints. Therefore, the authors attempted to answer the question of whether a technique of lower limbs movement during the phase of sprint maximum velocity significantly correlates with the time of running over this section. A group of 14 young people from the Lower Silesia Voivodeship Team participated in the experiment. A Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using Noraxon MyoMotion system. There were observed statistically significant relationships between sprint time over a section from 15 to 25 m and left hip rotation (positive) and between this time and left and right ankle joint dorsi-plantar flexion (negative). During the maximum velocity phase of a 30 m sprint, the effect of dorsi-plantar flexion performed in the whole range of motion was found to be beneficial. This can be attributed to the use of elastic energy released in the stride cycle. Further, hip rotation should be minimized, which makes the stride aligned more along a line of running (a straight line) instead of from side to side.

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.

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.

High-efficiency toroidal current drive using low-phase-velocity kinetic Alfven waves

International Nuclear Information System (INIS)

Puri, S.

1991-09-01

A method for obtaining efficient current drive in Tokamaks using low-phase-velocity (v ρ = ω/K parallel ∝ 0.1v te ) kinetic Alfen wave is proposed. The wave momentum, imparted primarily to the trapped electrons by Landau damping, is stored as the canonical angular momentum via the Ware pinch. In steady state, collisions restore the pinched electrons to their original phase-space configuration, in the process releasing the stored canonical angular momentum to the background ions and electrons in proportion to the respective collision frequencies. Despite the loss of a part of the original impulse to the plasma ions, well over half the wave momentum is ultimately delivered to the bulk-plasma electrons, resulting in an efficient current drive. A normalized current-drive efficiency γ = R 0 20 > I/P ∝ 2 would be feasible using the subthermal kinetic-Alfen-wave current drive in a Tokamak of reactor parameters. Optimum antenna loading conditions are described. The problem of accessibility is discussed. In an elongated, high-β plasma with a density dependence n e ∝ (1-ρ 2 ) Χn , accessibility is restricted to ρ > or approx. 3/(4A Χn ), where A is the aspect ratio. For current drive at still lower values of ρ, operation in conjunction with fast-wave current drive is suggested. (orig.)

Angular momentum of phonons and its application to single-spin relaxation

Science.gov (United States)

Nakane, Jotaro J.; Kohno, Hiroshi

2018-05-01

We reexamine the relaxation process of a single spin embedded in an elastic medium, a problem studied recently by Garanin and Chudnovsky (GC) [Phys. Rev. B 92, 024421 (2015), 10.1103/PhysRevB.92.024421] from the viewpoint of angular-momentum transfer. Using Noether's theorem, we identify two distinct angular momenta of the medium, one Newtonian discussed by GC and the other field-theoretical, both of which consist of an orbital part and a spin part. For both angular momenta, we found that the orbital part is as essential as the spin part in the relaxation process. In particular, the angular-momentum transfer from the (real) spin to the Newtonian orbital part may be considered as an incipient rotation that leads to the Einstein-de Haas effect.

Low-dimensional organization of angular momentum during walking on a narrow beam.

Science.gov (United States)

Chiovetto, Enrico; Huber, Meghan E; Sternad, Dagmar; Giese, Martin A

2018-01-08

Walking on a beam is a challenging motor skill that requires the regulation of upright balance and stability. The difficulty in beam walking results from the reduced base of support compared to that afforded by flat ground. One strategy to maintain stability and hence avoid falling off the beam is to rotate the limb segments to control the body's angular momentum. The aim of this study was to examine the coordination of the angular momentum variations during beam walking. We recorded movement kinematics of participants walking on a narrow beam and computed the angular momentum contributions of the body segments with respect to three different axes. Results showed that, despite considerable variability in the movement kinematics, the angular momentum was characterized by a low-dimensional organization based on a small number of segmental coordination patterns. When the angular momentum was computed with respect to the beam axis, the largest fraction of its variation was accounted for by the trunk segment. This simple organization was robust and invariant across all participants. These findings support the hypothesis that control strategies for complex balancing tasks might be easier to understand by investigating angular momentum instead of the segmental kinematics.

Angular distributions of particles sputtered from polycrystalline platinum by low-energy ions

International Nuclear Information System (INIS)

Chernysh, V.S.; Eckstein, W.; Haidarov, A.A.; Kulikauskas, V.S.; Mashkova, E.S.; Molchanov, V.A.

2000-01-01

The results of an experimental study and a computer simulation with the TRIM.SP code of the angular distributions of atoms sputtered from polycrystalline platinum under 3-9 keV Ne + bombardment at normal ion incidence are presented. It was found that angular distributions of sputtered atoms are overcosine and that their shape is practically independent of an ion energy. Comparison with the previously obtained data for He + and Ar + ions have shown that the shape of the angular distribution does not depend on the bombarding ion species. Good agreement between experimental results and computer simulation data was found. Computer simulations of the partial angular distributions of Pt atoms ejected due to various sputtering mechanisms for Ne ion bombardment were performed and the comparison with corresponding data for He and Ar bombarding was made. The role of different mechanisms in the formation of angular distributions of sputtered atoms has been analyzed

Orbital-angular-momentum entanglement in turbulence

CSIR Research Space (South Africa)

Hamadou Ibrahim, A

2013-06-01

Full Text Available The turbulence-induced decay of orbital-angular-momentum (OAM) entanglement between two photons is investigated numerically and experimentally. To compare our resultswith previouswork,we simulate the turbulent atmosphere with a single phase screen...

Orbital angular momentum of a high-order Bessel light beam

International Nuclear Information System (INIS)

Volke-Sepulveda, K; Garces-Chavez, V; Chavez-Cerda, S; Arlt, J; Dholakia, K

2002-01-01

The orbital angular momentum density of Bessel beams is calculated explicitly within a rigorous vectorial treatment. This allows us to investigate some aspects that have not been analysed previously, such as the angular momentum content of azimuthally and radially polarized beams. Furthermore, we demonstrate experimentally the mechanical transfer of orbital angular momentum to trapped particles in optical tweezers using a high-order Bessel beam. We set transparent particles of known dimensions into rotation, where the sense of rotation can be reversed by changing the sign of the singularity. Quantitative results are obtained for rotation rates. This paper's animations are available from the Multimedia Enhancements page

A Core Set Based Large Vector-Angular Region and Margin Approach for Novelty Detection

Directory of Open Access Journals (Sweden)

Jiusheng Chen

2016-01-01

Full Text Available A large vector-angular region and margin (LARM approach is presented for novelty detection based on imbalanced data. The key idea is to construct the largest vector-angular region in the feature space to separate normal training patterns; meanwhile, maximize the vector-angular margin between the surface of this optimal vector-angular region and abnormal training patterns. In order to improve the generalization performance of LARM, the vector-angular distribution is optimized by maximizing the vector-angular mean and minimizing the vector-angular variance, which separates the normal and abnormal examples well. However, the inherent computation of quadratic programming (QP solver takes O(n3 training time and at least O(n2 space, which might be computational prohibitive for large scale problems. By (1+ε  and  (1-ε-approximation algorithm, the core set based LARM algorithm is proposed for fast training LARM problem. Experimental results based on imbalanced datasets have validated the favorable efficiency of the proposed approach in novelty detection.

Photoelectron and ICD electron angular distributions from fixed-in-space neon dimers

International Nuclear Information System (INIS)

Jahnke, T; Czasch, A; Schoeffler, M; Schoessler, S; Kaesz, M; Titze, J; Kreidi, K; Grisenti, R E; Staudte, A; Jagutzki, O; Schmidt, L Ph H; Semenov, S K; Cherepkov, N A; Schmidt-Boecking, H; Doerner, R

2007-01-01

We report on molecular frame angular distributions of 2s photoelectrons and electrons emitted by interatomic Coulombic decay from neon dimers. We found that the measured angular distribution of the photoelectron strongly depends on the environment of the cluster. The experimental results are in excellent agreement with frozen core Hartree-Fock calculations. The ICD electrons show slight variations in their angular distribution for different kinetic energies

Auditory velocity discrimination in the horizontal plane at very high velocities.

Science.gov (United States)

Frissen, Ilja; Féron, François-Xavier; Guastavino, Catherine

2014-10-01

We determined velocity discrimination thresholds and Weber fractions for sounds revolving around the listener at very high velocities. Sounds used were a broadband white noise and two harmonic sounds with fundamental frequencies of 330 Hz and 1760 Hz. Experiment 1 used velocities ranging between 288°/s and 720°/s in an acoustically treated room and Experiment 2 used velocities between 288°/s and 576°/s in a highly reverberant hall. A third experiment addressed potential confounds in the first two experiments. The results show that people can reliably discriminate velocity at very high velocities and that both thresholds and Weber fractions decrease as velocity increases. These results violate Weber's law but are consistent with the empirical trend observed in the literature. While thresholds for the noise and 330 Hz harmonic stimulus were similar, those for the 1760 Hz harmonic stimulus were substantially higher. There were no reliable differences in velocity discrimination between the two acoustical environments, suggesting that auditory motion perception at high velocities is robust against the effects of reverberation. Copyright © 2014 Elsevier B.V. All rights reserved.

Angular momentum transport and evolution of lopsided galaxies

Science.gov (United States)

Saha, Kanak; Jog, Chanda J.

2014-10-01

The surface brightness distribution in the majority of stellar galactic discs falls off exponentially. Often what lies beyond such a stellar disc is the neutral hydrogen gas whose distribution also follows a nearly exponential profile at least for a number of nearby disc galaxies. Both the stars and gas are commonly known to host lopsided asymmetry especially in the outer parts of a galaxy. The role of such asymmetry in the dynamical evolution of a galaxy has not been explored so far. Following Lindblad's original idea of kinematic density waves, we show that the outer part of an exponential disc is ideally suitable for hosting lopsided asymmetry. Further, we compute the transport of angular momentum in the combined stars and gas disc embedded in a dark matter halo. We show that in a pure star and gas disc, there is a transition point where the free precession frequency of a lopsided mode, Ω - κ, changes from retrograde to prograde and this in turn reverses the direction of angular momentum flow in the disc leading to an unphysical behaviour. We show that this problem is overcome in the presence of a dark matter halo, which sets the angular momentum flow outwards as required for disc evolution, provided the lopsidedness is leading in nature. This, plus the well-known angular momentum transport in the inner parts due to spiral arms, can facilitate an inflow of gas from outside perhaps through the cosmic filaments.

Molecular frame and recoil frame angular distributions in dissociative photoionization of small molecules

International Nuclear Information System (INIS)

Lucchese, R R; Carey, R; Elkharrat, C; Houver, J C; Dowek, D

2008-01-01

Photoelectron angular distributions in the dipole approximation can be written with respect to several different reference frames. A brief review of the molecular frame and recoil frame are given. Experimentally, one approach for obtaining such angular distributions is through angle-resolved coincidence measurements of dissociative ionization. If the system dissociates into two heavy fragments, then the recoil frame angular distribution can be measured. Computed molecular frame and recoil frame photoelectron angular distributions are compared to experimental data for the Cl 2p ionization of CH 3 Cl.

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

Spatial Angular Compounding for Elastography without the Incompressibility Assumption

OpenAIRE

Rao, Min; Varghese, Tomy

2005-01-01

Spatial-angular compounding is a new technique that enables the reduction of noise artifacts in ultrasound elastography. Previous results using spatial angular compounding, however, were based on the use of the tissue incompressibility assumption. Compounded elastograms were obtained from a spatially-weighted average of local strain estimated from radiofrequency echo signals acquired at different insonification angles. In this paper, we present a new method for reducing the noise artifacts in...

Reaction 40Ca+natCu at 35 MeV/nucleon measured with the AMPHORA multidetector. Study of the excitation energy and angular momentum of the reconstructed projectile-like fragment

International Nuclear Information System (INIS)

Elhage, H.

1992-10-01

We have studied the reaction of 40 Ca with nat Cu at 35 MeV/nucleon with the AMPHORA multidetector. Three different reaction models were developed and we have shown that a simulation of the AMPHORA response is necessary to interpret the experimental results. Only two-body events were analyzed. Kinematic selection criterions, based on relative velocity, were used in order to isolate particles and residues coming from the de-excitation of the projectile-like fragment. The reconstitution of such a nucleus allowed to define the reaction plane and to calculate the energy balance event-by-event. We have proposed a method to determine the angular momentum based on the emission asymmetry of the light particles with respect to the normal to the reaction plane. The estimated angular momenta are in good agreement with the theoretical predictions. The projectile-like fragment temperature was estimated from the energy spectra of the light particles. The independent determination of the excitation energy, temperature and angular momentum allowed to calculate the level density parameter. This quantity does not evolve with the excitation energy and is equal to A/8. The projectile-like fragment de-excitation mode is mainly evaporation

Problems of angular momentum projection in nuclear physics

Energy Technology Data Exchange (ETDEWEB)

Sorensen, R A [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

1977-05-09

In nuclear models approximate wave functions are often used which do not have sharp angular momentum as required of the exact wave functions. It seems obvious that model wave functions of this type should be improved by projection onto states of good angular momentum. It is not the purpose of this paper to discuss the technical difficulties of projection (which can be formidable for many particle systems), but rather to present in an elementary way certain fundamental ambiguities in the use of projection. An application to high spin states near the yrast line is suggested.

Angular momentum fuctuation energy in the cranking model

International Nuclear Information System (INIS)

Goodman, A.L.

1979-01-01

Angular momentum is approximately projected from Hartree-Fock-Bogoliubov cranked (HFBC) wave functions. At each J the projected energy is Esub(proj)approximately Esub(HFBC). The spin-dependent fluctuation ΔJ includes contributions from Jsub(y) and Jsub(z) as well as Jsub(x). There are no correlations in the three angular momentum components. Projected energies are calculated for 168 170 Yb and 174 Hf. When compared to experimental energies, the projected spectra are less compressed than the HFBC spectra. At low spins the projected and experimental energies are in good agreement. (Aut.)

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.

Angular distributions of nucleons emitted in high energy hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1983-01-01

Angular distributions of ''fast'' protons, of kinetic energy from about 20 to about 400 MeV, emitted in pion-xenon nucleus collisions at 3.5 GeV/c momentum were studied in two groups of events - when particles are produced and when particle production does not occur. The distributions are practically the same in both the groups of events and in subgroups of events with various multiplicities of emitted protons. Comparison of angular distributions of protons emitted in pion-xenon nucleus collisions at 3.5 GeV/c momentum with corresponding angular distributions of protons emitted in proton-emulsion collisions at 300-400 GeV/c momentum is performed. Results obtained allow to conclude that average value of the nucleon emission angle and the nucleon angular distributions do not depend practically on the nuclear matter layer thickness the incident hadron collided with. Fast nucleons emitted from the target nucleus seem did not interact inside the parent nucleus. Fast nucleon angular distributions do not depend on the energy of incident hadron, they are the same for pion-nucleus and for proton-nucleus collisions as well

Microstructural evolution of bainitic steel severely deformed by equal channel angular pressing.

Science.gov (United States)

Nili-Ahmadabadi, M; Haji Akbari, F; Rad, F; Karimi, Z; Iranpour, M; Poorganji, B; Furuhara, T

2010-09-01

High Si bainitic steel has been received much of interest because of combined ultra high strength, good ductility along with high wear resistance. In this study a high Si bainitic steel (Fe-0.22C-2.0Si-3.0Mn) was used with a proper microstructure which could endure severe plastic deformation. In order to study the effect of severe plastic deformation on the microstructure and properties of bainitic steel, Equal Channel Angular Pressing was performed in two passes at room temperature. Optical, SEM and TEM microscopies were used to examine the microstructure of specimens before and after Equal Channel Angular Pressing processing. X-ray diffraction was used to measure retained austenite after austempering and Equal Channel Angular Pressing processing. It can be seen that retained austenite picks had removed after Equal Channel Angular Pressing which could attributed to the transformation of austenite to martensite during severe plastic deformation. Enhancement of hardness values by number of Equal Channel Angular Pressing confirms this idea.

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.)

NEW MASER EMISSION FROM NONMETASTABLE AMMONIA IN NGC 7538. III. DETECTION OF THE (10,6) TRANSITION AND A VELOCITY GRADIENT

Energy Technology Data Exchange (ETDEWEB)

Hoffman, Ian M., E-mail: ihoffman@wittenberg.edu [Physics Department Wittenberg University, Springfield, OH 45501 (United States)

2012-11-01

We present the first astronomical detection of the {sup 14}NH{sub 3} (J, K) = (10, 6) line: nonthermal emission at several velocities in the Galactic star-forming region NGC 7538. Using the Very Large Array we have imaged the (10,6) and (9,6) ammonia masers at several positions within NGC 7538 IRS 1. The individual sources have angular sizes {approx}< 0.1 arcsec corresponding to brightness temperatures T{sub B} {approx}> 10{sup 6} K. We apply the pumping model of Brown and Cragg, confirming the conjecture that multiple ortho-ammonia masers can occur with the same value of K. The positions and velocities of the (10,6) and (9,6) masers are modeled as motion in a possible disk or torus and are discussed in the context of recent models of the region.

Recursive generation of Cartesian angular momentum coupling trees for SO(3)

International Nuclear Information System (INIS)

Sherborne, B.S.; Stedman, G.E.

1990-01-01

Two computer algorithms are evaluated for the reduction of angular momentum coupling trees with vector (j=1) terminals with a Cartesian choice of basis as used in nonlinear optics. Rather than employ advanced tensor algebra, both methods essentially iterate in distinct ways the basic techniques of angular momentum coupling. Turbo Pascal programs implementing these algorithms are presented and compared. The accompanying analysis integrates the Cartesian tensor approach and the diagrammatic approach to the solution of problems in nonlinear optics. The programs generate TeX files for the relevant angular momentum diagrams. (orig.)

Angular momentum transfer in deep inelastic heavy ion collisions. Part 2

International Nuclear Information System (INIS)

Barbosa, V.C.; Soares, P.C.; Oliveira, Edgar C. de; Gomes, Luiz Carlos

1985-01-01

The Fokker-Planck equation which describes the angular momentum transfer in deep inelastic heavy ion collisions is solved by a stochastic simulation procedure. The fusion cross section calculation is discussed. The calculations show that the critical orbital angular momentum does not play such a special role as in the deterministic case. The results of all the angular momentum transfer and their fluctuations are calculated and compared with experimental results for the reactions 86 Kr+ 154 Sm at 610 MeV, 165 Ho+ 148 Sm, and 165 Ho+ 176 Yb at 1400 MeV. (Author) [pt

Helicon modes in uniform plasmas. III. Angular momentum

International Nuclear Information System (INIS)

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

2015-01-01

Helicons are electromagnetic waves with helical phase fronts propagating in the whistler mode in magnetized plasmas and solids. They have similar properties to electromagnetic waves with angular momentum in free space. Helicons are circularly polarized waves carrying spin angular momentum and orbital angular momentum due to their propagation around the ambient magnetic field B 0 . These properties have not been considered in the community of researchers working on helicon plasma sources, but are the topic of the present work. The present work focuses on the field topology of helicons in unbounded plasmas, not on helicon source physics. Helicons are excited in a large uniform laboratory plasma with a magnetic loop antenna whose dipole axis is aligned along or across B 0 . The wave fields are measured in orthogonal planes and extended to three dimensions (3D) by interpolation. Since density and B 0 are uniform, small amplitude waves from loops at different locations can be superimposed to generate complex antenna patterns. With a circular array of phase shifted loops, whistler modes with angular and axial wave propagation, i.e., helicons, are generated. Without boundaries radial propagation also arises. The azimuthal mode number m can be positive or negative while the field polarization remains right-hand circular. The conservation of energy and momentum implies that these field quantities are transferred to matter which causes damping or reflection. Wave-particle interactions with fast electrons are possible by Doppler shifted resonances. The transverse Doppler shift is demonstrated. Wave-wave interactions are also shown by showing collisions between different helicons. Whistler turbulence does not always have to be created by nonlinear wave-interactions but can also be a linear superposition of waves from random sources. In helicon collisions, the linear and/or orbital angular momenta can be canceled, which results in a great variety of field topologies. The work

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.;

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…

Self-Adjoint Angular Flux Equation for Coupled Electron-Photon Transport

International Nuclear Information System (INIS)

Liscum-Powell, J.L.; Lorence, L.J. Jr.; Morel, J.E.; Prinja, A.K.

1999-01-01

Recently, Morel and McGhee described an alternate second-order form of the transport equation called the self adjoint angular flux (SAAF) equation that has the angular flux as its unknown. The SAAF formulation has all the advantages of the traditional even- and odd-parity self-adjoint equations, with the added advantages that it yields the full angular flux when it is numerically solved, it is significantly easier to implement reflective and reflective-like boundary conditions, and in the appropriate form it can be solved in void regions. The SAAF equation has the disadvantage that the angular domain is the full unit sphere and, like the even- and odd- parity form, S n source iteration cannot be implemented using the standard sweeping algorithm. Also, problems arise in pure scattering media. Morel and McGhee demonstrated the efficacy of the SAAF formulation for neutral particle transport. Here we apply the SAAF formulation to coupled electron-photon transport problems using multigroup cross-sections from the CEPXS code and S n discretization

Self-adjoint angular flux equation for coupled electron-photon transport

International Nuclear Information System (INIS)

Liscum-Powell, J.L.; Prinja, A.K.; Morel, J.E.; Lorence, L.J. Jr.

1999-01-01

Recently, Morel and McGhee described an alternate second-order form of the transport equation called the self-adjoint angular flux (SAAF) equation that has the angular flux as its unknown. The SAAF formulation has all the advantages of the traditional even- and odd-parity self-adjoint equations, with the added advantages that it yields the full angular flux when it is numerically solved, it is significantly easier to implement reflective and reflective-like boundary conditions, and in the appropriate form it can be solved in void regions. The SAAF equation has the disadvantage that the angular domain is the full unit sphere, and, like the even- and odd-parity form, S n source iteration cannot be implemented using the standard sweeping algorithm. Also, problems arise in pure scattering media. Morel and McGhee demonstrated the efficacy of the SAAF formulation for neutral particle transport. Here, the authors apply the SAAF formulation to coupled electron-photon transport problems using multigroup cross sections from the CEPXS code and S n discretization

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.

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

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)

Shape coexistence in 72Kr at finite angular momentum

International Nuclear Information System (INIS)

Almehed, Daniel; Walet, Niels R.

2004-01-01

We investigate shape coexistence in a rotating nucleus. We concentrate on the case of 72 Kr which exhibits an interesting interplay between prolate and oblate shaped states as a function of angular momentum. The calculation uses the local harmonic version of the method of self-consistent adiabatic large-amplitude collective motion. We analyse how the collective behaviour of the system changes with angular momentum and we focus on the role of non-axial shapes

Superconducting RF for Low-Velocity and Intermediate-Velocity Beams

CERN Document Server

Grimm, Terry L

2005-01-01

Existing superconducting radio frequency (SRF) linacs are used to accelerate ions (protons through uranium) with velocities less than about 15% the speed of light, or electrons with velocities approximately equal to the speed of light. In the last ten years, prototype SRF cavities have completely covered the remaining range of velocities. They have demonstrated that SRF linacs will be capable of accelerating electrons from rest up to the speed of light, and ions from less than 1% up to the speed of light. When the Spallation Neutron Source is operational, SRF ion linacs will have covered the full range of velocities except for v/c ~ 0.15 to v/c ~ 0.5. A number of proposed projects (RIA, EURISOL) would span the latter range of velocities. Future SRF developments will have to address the trade-offs associated with a number of issues, including high gradient operation, longitudinal and transverse acceptance, microphonics, Lorentz detuning, operating temperature, cryogenic load, number of gaps or cells per cavity...

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)

Angular overlap model in actinides

International Nuclear Information System (INIS)

Gajek, Z.; Mulak, J.

1991-01-01

Quantitative foundations of the Angular Overlap Model in actinides based on ab initio calculations of the crystal field effect in the uranium (III) (IV) and (V) ions in various crystals are presented. The calculations justify some common simplifications of the model and fix up the relations between the AOM parameters. Traps and limitations of the AOM phenomenology are discussed

Angular overlap model in actinides

Energy Technology Data Exchange (ETDEWEB)

Gajek, Z.; Mulak, J. (Polska Akademia Nauk, Wroclaw (PL). Inst. Niskich Temperatur i Badan Strukturalnych)

1991-01-01

Quantitative foundations of the Angular Overlap Model in actinides based on ab initio calculations of the crystal field effect in the uranium (III) (IV) and (V) ions in various crystals are presented. The calculations justify some common simplifications of the model and fix up the relations between the AOM parameters. Traps and limitations of the AOM phenomenology are discussed.

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

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.

Angular circulation speed of tablets in a vibratory tablet coating pan.

Science.gov (United States)

Kumar, Rahul; Wassgren, Carl

2013-03-01

In this work, a single tablet model and a discrete element method (DEM) computer simulation are developed to obtain the angular circulation speed of tablets in a vibratory tablet coating pan for range of vibration frequencies and amplitudes. The models identify three important dimensionless parameters that influence the speed of the tablets: the dimensionless amplitude ratio (a/R), the Froude number (aω2/g), and the tablet-wall friction coefficient, where a is the peak vibration amplitude at the drum center, ω is the vibration angular frequency, R is the drum radius, and g is the acceleration due to gravity. The models predict that the angular circulation speed of tablets increases with an increase in each of these parameters. The rate of increase in the angular circulation speed is observed to decrease for larger values of a/R. The angular circulation speed reaches an asymptote beyond a tablet-wall friction coefficient value of about 0.4. Furthermore, it is found that the Froude number should be greater than one for the tablets to start circulating. The angular circulation speed increases as Froude number increases but then does not change significantly at larger values of the Froude number. Period doubling, where the motion of the bed is repeated every two cycles, occurs at a Froude number larger than five. The single tablet model, although much simpler than the DEM model, is able to predict the maximum circulation speed (the limiting case for a large value of tablet-wall friction coefficient) as well as the transition to period doubling.

Angular dependence of the nanoDot OSL dosimeter

International Nuclear Information System (INIS)

Kerns, James R.; Kry, Stephen F.; Sahoo, Narayan; Followill, David S.; Ibbott, Geoffrey S.

2011-01-01

Purpose: Optically stimulated luminescent detectors (OSLDs) are quickly gaining popularity as passive dosimeters, with applications in medicine for linac output calibration verification, brachytherapy source verification, treatment plan quality assurance, and clinical dose measurements. With such wide applications, these dosimeters must be characterized for numerous factors affecting their response. The most abundant commercial OSLD is the InLight/OSL system from Landauer, Inc. The purpose of this study was to examine the angular dependence of the nanoDot dosimeter, which is part of the InLight system. Methods: Relative dosimeter response data were taken at several angles in 6 and 18 MV photon beams, as well as a clinical proton beam. These measurements were done within a phantom at a depth beyond the build-up region. To verify the observed angular dependence, additional measurements were conducted as well as Monte Carlo simulations in MCNPX. Results: When irradiated with the incident photon beams parallel to the plane of the dosimeter, the nanoDot response was 4% lower at 6 MV and 3% lower at 18 MV than the response when irradiated with the incident beam normal to the plane of the dosimeter. Monte Carlo simulations at 6 MV showed similar results to the experimental values. Examination of the results in Monte Carlo suggests the cause as partial volume irradiation. In a clinical proton beam, no angular dependence was found. Conclusions: A nontrivial angular response of this OSLD was observed in photon beams. This factor may need to be accounted for when evaluating doses from photon beams incident from a variety of directions.

Distribution of the angular momentum in the Galaxy and M31

International Nuclear Information System (INIS)

Einasto, J.; Traat, P.

1977-01-01

The angular momentum distribution of the Galaxy and of the Andromeda galaxy M31 has been calculated separately for the disk and halo population. The disk was approximated with a ring. The distribution of the angular momentum in the disk and the halo is different

Diffraction by a plane angular sector, a new derivation

DEFF Research Database (Denmark)

Hansen, Thokild B.

1990-01-01

An alternative derivation is given for the exact solution to the scattering problem in which a Hertz dipole illuminates a perfectly conducting plane angular sector. Specifically, the Ohm-Rayleigh method is used rather than that of Satterwhite (1969)......An alternative derivation is given for the exact solution to the scattering problem in which a Hertz dipole illuminates a perfectly conducting plane angular sector. Specifically, the Ohm-Rayleigh method is used rather than that of Satterwhite (1969)...

Effects of angular misalignment on optical klystron undulator radiation

Energy Technology Data Exchange (ETDEWEB)

Mishra, G., E-mail: gmishra_dauniv@yahoo.co.in; Prakash, Bramh; Gehlot, Mona

2015-11-21

In this paper ,we analyze the important effects of optical klystron undulator radiation with an angular offset of the relativistic electron beam in the second undulator section. An anlytical expression for the undulator radiation is obtained through a transparent and simple procedure.It is shown that the effects of the angular offset is more severe for longer undulator lengths and with higher dispersive field strengths.Both these effects are less pronounced for undulators with large K values.

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

Characteristic evolutions in numerical relativity using six angular patches

Energy Technology Data Exchange (ETDEWEB)

Reisswig, Christian [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Golm (Germany); Bishop, Nigel T [Department of Mathematical Sciences, University of South Africa, PO Box 392, Unisa 0003, South Africa (South Africa); Lai, Chi Wai [Department of Mathematical Sciences, University of South Africa, PO Box 392, Unisa 0003, South Africa (South Africa); Thornburg, Jonathan [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Golm (Germany); Szilagyi, Bela [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, D-14476 Golm (Germany)

2007-06-21

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.

Problems of angular momentum projection in nuclear physics

International Nuclear Information System (INIS)

Sorensen, R.A.

1977-01-01

In nuclear models approximate wave functions are often used which do not have sharp angular momentum as required of the exact wave functions. It seems obvious that model wave functions of this type should be improved by projection onto states of good angular momentum. It is not the purpose of this paper to discuss the technical difficulties of projection (which can be formidable for many particle systems), but rather to present in an elementary way certain fundamental ambiguities in the use of projection. An application to high spin states near the yrast line is suggested. (Auth.)

Gamma-ray angular distribution and correlation measurement. II

International Nuclear Information System (INIS)

Twin, P.J.

1975-01-01

Angular correlations of γ-rays following nuclear reactions depend, in general, on some alignment of the γ-emitting initial state. The methods of alignment are briefly discussed and then the techniques and experimental methods associated with direct angular distributions, particle-gamma correlations, gamma-gamma correlations and linear polarization correlations are dealt with. Finally the inherent ambiguities which arise when different spin and delta values give identical correlations are discussed for the simple direct and particle-gamma correlations together with the question whether the larger information content of gamma-gamma and linear polarization correlations can resolve these ambiguities. (Auth.)

Mean Velocity vs. Mean Propulsive Velocity vs. Peak Velocity: Which Variable Determines Bench Press Relative Load With Higher Reliability?

Science.gov (United States)

García-Ramos, Amador; Pestaña-Melero, Francisco L; Pérez-Castilla, Alejandro; Rojas, Francisco J; Gregory Haff, G

2018-05-01

García-Ramos, A, Pestaña-Melero, FL, Pérez-Castilla, A, Rojas, FJ, and Haff, GG. Mean velocity vs. mean propulsive velocity vs. peak velocity: which variable determines bench press relative load with higher reliability? J Strength Cond Res 32(5): 1273-1279, 2018-This study aimed to compare between 3 velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and peak velocity [PV]): (a) the linearity of the load-velocity relationship, (b) the accuracy of general regression equations to predict relative load (%1RM), and (c) the between-session reliability of the velocity attained at each percentage of the 1-repetition maximum (%1RM). The full load-velocity relationship of 30 men was evaluated by means of linear regression models in the concentric-only and eccentric-concentric bench press throw (BPT) variants performed with a Smith machine. The 2 sessions of each BPT variant were performed within the same week separated by 48-72 hours. The main findings were as follows: (a) the MV showed the strongest linearity of the load-velocity relationship (median r = 0.989 for concentric-only BPT and 0.993 for eccentric-concentric BPT), followed by MPV (median r = 0.983 for concentric-only BPT and 0.980 for eccentric-concentric BPT), and finally PV (median r = 0.974 for concentric-only BPT and 0.969 for eccentric-concentric BPT); (b) the accuracy of the general regression equations to predict relative load (%1RM) from movement velocity was higher for MV (SEE = 3.80-4.76%1RM) than for MPV (SEE = 4.91-5.56%1RM) and PV (SEE = 5.36-5.77%1RM); and (c) the PV showed the lowest within-subjects coefficient of variation (3.50%-3.87%), followed by MV (4.05%-4.93%), and finally MPV (5.11%-6.03%). Taken together, these results suggest that the MV could be the most appropriate variable for monitoring the relative load (%1RM) in the BPT exercise performed in a Smith machine.

Angular distribution of diffuse reflectance from incoherent multiple scattering in turbid media.

Science.gov (United States)

Gao, M; Huang, X; Yang, P; Kattawar, G W

2013-08-20

The angular distribution of diffuse reflection is elucidated with greater understanding by studying a homogeneous turbid medium. We modeled the medium as an infinite slab and studied the reflection dependence on the following three parameters: the incident direction, optical depth, and asymmetry factor. The diffuse reflection is produced by incoherent multiple scattering and is solved through radiative transfer theory. At large optical depths, the angular distribution of the diffuse reflection with small incident angles is similar to that of a Lambertian surface, but, with incident angles larger than 60°, the angular distributions have a prominent reflection peak around the specular reflection angle. These reflection peaks are found originating from the scattering within one transport mean free path in the top layer of the medium. The maximum reflection angles for different incident angles are analyzed and can characterize the structure of angular distributions for different asymmetry factors and optical depths. The properties of the angular distribution can be applied to more complex systems for a better understanding of diffuse reflection.

Velocity-resolved [Ne III] from X-ray irradiated Sz 102 microjets

Energy Technology Data Exchange (ETDEWEB)

Liu, Chun-Fan; Shang, Hsien [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10641, Taiwan (China); Walter, Frederick M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Herczeg, Gregory J. [The Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

2014-05-10

Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III] λ3869 emission from the microjets of Sz 102, a low-mass young star in Lupus III. Spectroastrometric analyses of two-dimensional [Ne III] spectra obtained from archival high-dispersion (R ≈ 33, 000) Very Large Telescope/UVES data suggest that the emission consists of two velocity components spatially separated by ∼0.''3, or a projected distance of ∼60 AU. The stronger redshifted component is centered at ∼ + 21 km s{sup –1} with a line width of ∼140 km s{sup –1}, and the weaker blueshifted component at ∼ – 90 km s{sup –1} with a line width of ∼190 km s{sup –1}. The two components trace velocity centroids of the known microjets and show large line widths that extend across the systemic velocity, suggesting their potential origins in wide-angle winds that may eventually collimate into jets. Optical line ratios indicate that the microjets are hot (T ≲ 1.6 × 10{sup 4} K) and ionized (n{sub e} ≳ 5.7 × 10{sup 4} cm{sup –3}). The blueshifted component has ∼13% higher temperature and ∼46% higher electron density than the redshifted counterpart, forming a system of an asymmetric pair of jets. The detection of the [Ne III] λ3869 line with the distinct velocity profile suggests that the emission originates in flows that may have been strongly ionized by deeply embedded hard X-ray sources, most likely generated by magnetic processes. The discovery of [Ne III] λ3869 emission along with other optical forbidden lines from Sz 102 supports the picture of wide-angle winds surrounding magnetic loops in the close vicinity of the young star. Future high-sensitivity X-ray imaging and high angular-resolution optical spectroscopy may help confirm the picture proposed.

PATTERN SPEEDS OF BARS AND SPIRAL ARMS FROM Hα VELOCITY FIELDS

International Nuclear Information System (INIS)

Fathi, K.; Pinol-Ferrer, N.; Beckman, J. E.; MartInez-Valpuesta, I.; Hernandez, O.; Carignan, C.

2009-01-01

We have applied the Tremaine-Weinberg method to 10 late-type barred spiral galaxies using data cubes, in Hα emission, from the FaNTOmM and GHAFAS Fabry-Perot spectrometers. We have combined the derived bar (and/or spiral) pattern speeds with angular frequency plots to measure the corotation radii for the bars in these galaxies. We base our results on a combination of this method with a morphological analysis designed to estimate the corotation radius to bar-length ratio using two independent techniques on archival near-infrared images, and although we are aware of the limitation of the application of the Tremaine-Weinberg method using Hα observations, we find consistently excellent agreement between bar and spiral arm parameters derived using different methods. In general, the corotation radius, measured using the Tremaine-Weinberg method, is closely related to the bar length, measured independently from photometry and consistent with previous studies. Our corotation/bar-length ratios and pattern speed values are in good agreement with general results from numerical simulations of bars. In systems with identified secondary bars, we measure higher Hα velocity dispersion in the circumnuclear regions, whereas in all the other galaxies, we detect flat velocity dispersion profiles. In the galaxies where the bar is almost purely stellar, Hα measurements are missing, and the Tremaine-Weinberg method yields the pattern speeds of the spiral arms. The excellent agreement between the Tremaine-Weinberg method results and the morphological analysis and bar parameters in numerical simulations suggests that although the Hα emitting gas does not obey the continuity equation, it can be used to derive the bar pattern speed. In addition, we have analyzed the Hα velocity dispersion maps to investigate signatures of secular evolution of the bars in these galaxies. The increased central velocity dispersion in the galaxies with secondary bars suggests that the formation of inner

Velocity-resolved [Ne III] from X-ray irradiated Sz 102 microjets

International Nuclear Information System (INIS)

Liu, Chun-Fan; Shang, Hsien; Walter, Frederick M.; Herczeg, Gregory J.

2014-01-01

Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III] λ3869 emission from the microjets of Sz 102, a low-mass young star in Lupus III. Spectroastrometric analyses of two-dimensional [Ne III] spectra obtained from archival high-dispersion (R ≈ 33, 000) Very Large Telescope/UVES data suggest that the emission consists of two velocity components spatially separated by ∼0.''3, or a projected distance of ∼60 AU. The stronger redshifted component is centered at ∼ + 21 km s –1 with a line width of ∼140 km s –1 , and the weaker blueshifted component at ∼ – 90 km s –1 with a line width of ∼190 km s –1 . The two components trace velocity centroids of the known microjets and show large line widths that extend across the systemic velocity, suggesting their potential origins in wide-angle winds that may eventually collimate into jets. Optical line ratios indicate that the microjets are hot (T ≲ 1.6 × 10 4 K) and ionized (n e ≳ 5.7 × 10 4 cm –3 ). The blueshifted component has ∼13% higher temperature and ∼46% higher electron density than the redshifted counterpart, forming a system of an asymmetric pair of jets. The detection of the [Ne III] λ3869 line with the distinct velocity profile suggests that the emission originates in flows that may have been strongly ionized by deeply embedded hard X-ray sources, most likely generated by magnetic processes. The discovery of [Ne III] λ3869 emission along with other optical forbidden lines from Sz 102 supports the picture of wide-angle winds surrounding magnetic loops in the close vicinity of the young star. Future high-sensitivity X-ray imaging and high angular-resolution optical spectroscopy may help confirm the picture proposed.

Nutritional status, oral hygiene and Angular cheilitis in schoolchildren in Cianjur district, West Java

Directory of Open Access Journals (Sweden)

Fatimah Boenjamin Partakusuma

2017-08-01

Full Text Available Background: Angular cheilitis is a lesion at the corner of the mouth. Clinically, it is visible as an erythema and ulceration that occasionally extend beyond the vermillion border onto the skin. Anemia in children is an issue of global nutritional problems that need attention. The objectives of the study  was to determine the association between nutritional status, oral hygiene  and angular cheilitis in elementary schoolchildren in District of Cianjur. Methods: This cross sectional study was conducted on 349 schoolchildren in five Subdistrict of Cianjur. Angular cheilitis status was determined based on the criteria set by Ohman (1986. Anhropometric status was determined by CDC BMI-for-age percentile growth chart. Anemia status was determine by the level of hemoglobin concentration using the HemoCue device. Oral hygiene was measured by OHI-S index. Results: The prevalence of angular cheilitis, anemia, wasting and poor oral hygiene were: 62.5%, 12,6%, 20.6%, and 67.3%, respectively. There are no relationships between  anthropometric status, oral hygiene and angular cheilitis. (p> 0.05. However there is a relationship significant relationship beween anemia and angular cheilitis (p <0.05. Logistic regression test showed that anemia is a risk factor on the occurrence of angular cheilitis. Conclusion: Anemia is a factor on the occurrence of angular cheilitis in schoolchildren in Cianjur.

Angular momentum in non-relativistic QED and photon contribution to spin of hydrogen atom

International Nuclear Information System (INIS)

Chen Panying; Ji Xiangdong; Xu Yang; Zhang Yue

2010-01-01

We study angular momentum in non-relativistic quantum electrodynamics (NRQED). We construct the effective total angular momentum operator by applying Noether's theorem to the NRQED lagrangian. We calculate the NRQED matching for the individual components of the QED angular momentum up to one loop. We illustrate an application of our results by the first calculation of the angular momentum of the ground state hydrogen atom carried in radiative photons, α em 3 /18π, which might be measurable in future atomic experiments.

Polarization-Dependent Measurements of Molecular Super Rotors with Oriented Angular Momenta

Science.gov (United States)

Murray, Matthew J.; Toro, Carlos; Liu, Qingnan; Mullin, Amy S.

2014-05-01

Controlling molecular motion would enable manipulation of energy flow between molecules. Here we have used an optical centrifuge to investigate energy transfer between molecular super rotors with oriented angular momenta. The polarizable electron cloud of the molecules interacts with the electric field of linearly polarized light that angularly accelerates over the time of the optical pulse. This process drives molecules into high angular momentum states that are oriented with the optical field and have energies far from equilibrium. High resolution transient IR spectroscopy reveals the dynamics of collisional energy transfer for these super excited rotors. The results of this study leads to a more fundamental understanding of energy balance in non-equilibrium environments and the physical and chemical properties of gases in a new regime of energy states. Results will be presented for several super rotor species including carbon monoxide, carbon dioxide, and acetylene. Polarization-dependent measurements reveal the extent to which the super rotors maintain spatial orientation of high angular momentum states.

Angular dependence of dose equivalent response of an albedo neutron dosimeter

International Nuclear Information System (INIS)

Torres, B.A.; Boswell, E.; Schwartz, R.B.

1994-01-01

The ANSI provides procedures for testing the performance of dosimetry services. Although neutron dose equivalent angular response studies are not now mandated, future standards may well require that such studies be performed. Current studies with an albedo dosimeter will yield information regarding the angular dependence of dose equivalent response for this type of personnel dosimeter. Preliminary data for bare 252 Cf fluences show a marked decrease in dosimeter reading with increasing angle. The response decreased by an approximate factor of four. For the horizontal orientation, the same response was noted from both positive and negative angles. However, for the vertical orientation, the response was unexplainably assymetric. We are also examining the response of the personnel badge in moderated 252 Cf fluences. Responses from the moderated and unmoderated 252 Cf fields and theoretical calculations of the neutron angular response will be compared. This information will assist in building a data base for future comparisons of neutron angular responses with other neutron albedo dosimeters and phantoms

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 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.

Two-dimensional angular momentum in the presence of long-range magnetic flux

International Nuclear Information System (INIS)

Jackiw, R.; Redlich, A.N.

1983-01-01

It is shown that eigenvalues of two-dimensional angular momentum remain integer valued in the magnetic field of a solenoid, contrary to published assertions that they are modified by the flux. For a vortex, flux does contribute, and the angular momentum can fractionize, as asserted in the literature, provided phases of wave functions are chosen consistently with the solenoid problem. Long-range effects of flux, the distinction between orbital and canonical angular momentum, and interactions with Cooper pairs are essential to this argument

Photofragment angular momentum distribution beyond the axial recoil approximation: Predissociation

International Nuclear Information System (INIS)

Kuznetsov, Vladislav V.; Vasyutinskii, Oleg S.

2007-01-01

We present the quantum mechanical expressions for the angular momentum distribution of the photofragments produced in slow predissociation. The paper is based on our recent theoretical treatment [J. Chem. Phys. 123, 034307 (2005)] of the recoil angle dependence of the photofragment multipole moments which explicitly treat the role of molecular axis rotation on the electronic angular momentum polarization of the fragments. The electronic wave function of the molecule was used in the adiabatic body frame representation. The rigorous expressions for the fragment state multipoles which have been explicitly derived from the scattering wave function formalism have been used for the case of slow predissociation where a molecule lives in the excited quasibound state much longer than a rotation period. Possible radial nonadiabatic interactions were taken into consideration. The optical excitation of a single rotational branch and the broadband incoherent excitation of all possible rotational branches have been analyzed in detail. The angular momentum polarization of the photofragments has been treated in the high-J limit. The polarization of the photofragment angular momenta predicted by the theory depends on photodissociation mechanism and can in many cases be significant

Transverse and Longitudinal Doppler Effects of the Sunbeam Spectra and Earth-Self Rotation and Orbital Velocities, the Mass of the Sun and Others

OpenAIRE

Nam, Sang Boo

2009-01-01

The transverse and longitudinal Doppler effects of the sunbeam spectra are shown to result in the earth parameters such as the earth-self rotation and revolution velocities, the earth orbit semi-major axis, the earth orbital angular momentum, the earth axial tilt, the earth orbit eccentricity, the local latitude and the mass of the sun. The sunbeam global positioning scheme is realized, including the earth orbital position. PACS numbers: 91.10.Fc, 95.10.Km, 91.10.Da, 91.10.Jf.

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.

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.

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.

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.

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;

Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines

Directory of Open Access Journals (Sweden)

P. Guio

Full Text Available The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron velocity distribution is separated into two distributions representing the distribution of the ambient electrons and the suprathermal electrons. The velocity distribution function of the ambient electrons is modelled by a near-Maxwellian distribution function in presence of a temperature gradient and a potential electric field. The velocity distribution function of the suprathermal electrons is derived from a numerical model of the angular energy flux spectrum obtained by solving the transport equation of electrons. The numerical method used to calculate the plasma dispersion function and the reduced velocity distribution is described. The numerical code is used with simulated data to evaluate the Doppler frequency asymmetry between the up- and downshifted plasma lines of the incoherent-scatter plasma lines at different wave vectors. It is shown that the observed Doppler asymmetry is more dependent on deviation from the Maxwellian through the thermal part for high-frequency radars, while for low-frequency radars the Doppler asymmetry depends more on the presence of a suprathermal population. It is also seen that the full evaluation of the plasma dispersion function gives larger Doppler asymmetry than the heat flow approximation for Langmuir waves with phase velocity about three to six times the mean thermal velocity. For such waves the moment expansion of the dispersion function is not fully valid and the full calculation of the dispersion function is needed.

Key words. Non-Maxwellian electron velocity distribution · Incoherent scatter plasma lines · EISCAT · Dielectric response function

Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines

Directory of Open Access Journals (Sweden)

P. Guio

1998-10-01

Full Text Available The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron velocity distribution is separated into two distributions representing the distribution of the ambient electrons and the suprathermal electrons. The velocity distribution function of the ambient electrons is modelled by a near-Maxwellian distribution function in presence of a temperature gradient and a potential electric field. The velocity distribution function of the suprathermal electrons is derived from a numerical model of the angular energy flux spectrum obtained by solving the transport equation of electrons. The numerical method used to calculate the plasma dispersion function and the reduced velocity distribution is described. The numerical code is used with simulated data to evaluate the Doppler frequency asymmetry between the up- and downshifted plasma lines of the incoherent-scatter plasma lines at different wave vectors. It is shown that the observed Doppler asymmetry is more dependent on deviation from the Maxwellian through the thermal part for high-frequency radars, while for low-frequency radars the Doppler asymmetry depends more on the presence of a suprathermal population. It is also seen that the full evaluation of the plasma dispersion function gives larger Doppler asymmetry than the heat flow approximation for Langmuir waves with phase velocity about three to six times the mean thermal velocity. For such waves the moment expansion of the dispersion function is not fully valid and the full calculation of the dispersion function is needed.Key words. Non-Maxwellian electron velocity distribution · Incoherent scatter plasma lines · EISCAT · Dielectric response function

Revisiting elastic anisotropy of biotite gneiss from the Outokumpu scientific drill hole based on new texture measurements and texture-based velocity calculations

Science.gov (United States)

Wenk, H.-R.; Vasin, R. N.; Kern, H.; Matthies, S.; Vogel, S. C.; Ivankina, T. I.

2012-10-01

A sample of biotite gneiss from the Outokumpu deep drilling project in Finland was investigated by Kern et al. (2008) for crystal preferred orientation and elastic anisotropy. Considerable differences between measured acoustic velocities and velocities calculated on the basis of texture patterns were observed. Measured P-wave anisotropy was 15.1% versus a Voigt average yielding 7.9%. Here we investigate the same sample with different methods and using different averaging techniques. Analyzing time-of-flight neutron diffraction data from Dubna-SKAT and LANSCE-HIPPO diffractometers with the Rietveld technique, much stronger preferred orientation for biotite is determined, compared to conventional pole-figure analysis reported previously. The comparison reveals important differences: HIPPO has much better counting statistics but pole figure coverage is poor. SKAT has better angular resolution. Using the new preferred orientation data and applying a self-consistent averaging method that takes grain shapes into account, close agreement of calculated and measured P-wave velocities is observed (12.6%). This is further improved by adding 0.1 vol.% flat micropores parallel to the biotite platelets in the simulation (14.9%).

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.

Angular momentum and incident-energy dependence of nucleus-nucleus interaction

International Nuclear Information System (INIS)

Yamaguchi, S.

1991-01-01

The purpose of this paper is to understand intuitively the origin of the angular momentum and incident-energy dependence of the nucleus-nucleus interaction on the basis of the totally- antisymmetrized many-body theory. With the aim of understanding the structure of the nucleus-nucleus interaction, we show first that the nucleus-nucleus interaction can be written by the use of the density-distribution function and the phase-space distribution function instead of using the many-body wave function itself. And we show that the structure change of the density-distribution function with the increase of the angular momentum causes the angular momentum dependence of the nucleus-nucleus interaction and that the incident-energy dependence of the nucleus-nucleus interaction originates from the structure change of the phase-space distribution function

Vector parametrization, partial angular momenta and unusual commutation relations in physics

International Nuclear Information System (INIS)

Gatti, Fabien; Nauts, Andre

2003-01-01

When studying an N-particle system by means of N-1 vectors i.e., by means of a vector parametrization, one unavoidably comes across several angular momenta: not only the total angular momentum of the system but also the various partial angular momenta corresponding to the motion of the various vectors. All these momenta can, in addition, be referred to a variety of reference frames. The use of vector parametrizations and partial angular momenta in physics greatly simplifies the classical as well as quantum expressions of the kinetic energy. The present paper is devoted to a detailed and rigorous study of the partial angular momenta and the various commutation relations they satisfy, in particular the unusual commutation relations whose origin is traced back to the very structure of the coordinate changes used to define the Body-Fixed (BF) frames. The direct quantization of the classical expressions of the kinetic energy obtained in the context of various vector parametrizations is also given in detail. It turns out to be an efficient extension of well-known quantization procedures to the case where supernumerary quasi-momenta are used. As an illustration, the case of a four-particle system is treated in detail for a particular choice of the BF frames. Finally, the analogies between the classical and quantum approaches are emphasized

Phase-space distributions and orbital angular momentum

Directory of Open Access Journals (Sweden)

Pasquini B.

2014-06-01

Full Text Available We review the concept of Wigner distributions to describe the phase-space distributions of quarks in the nucleon, emphasizing the information encoded in these functions about the quark orbital angular momentum.

On the complex angular momentum theory of scattering

International Nuclear Information System (INIS)

Thylwe, K.-E.

1983-01-01

A contribution to the theory of complex angular momentum techniques in the field of atomic and molecular collisions is given. A new, flexible representation of the scattering amplitude on the basis of realistic assumptions for the behaviour of the S matrix in the complex angular momentum plane is derived. The representation has the form of a sum of steepest-descent integrals, S-matrix residue terms and a symmetry-type background integral. The flexibility is due to the presence of two integer parameters which may be chosen conveniently so as to make the residue sums sufficiently convergent and to minimise the total number of important terms. (author)

Velocity correlations and spatial dependencies between neighbors in a unidirectional flow of pedestrians

Science.gov (United States)

Porzycki, Jakub; WÄ s, Jarosław; Hedayatifar, Leila; Hassanibesheli, Forough; Kułakowski, Krzysztof

2017-08-01

The aim of the paper is an analysis of self-organization patterns observed in the unidirectional flow of pedestrians. On the basis of experimental data from Zhang et al. [J. Zhang et al., J. Stat. Mech. (2011) P06004, 10.1088/1742-5468/2011/06/P06004], we analyze the mutual positions and velocity correlations between pedestrians when walking along a corridor. The angular and spatial dependencies of the mutual positions reveal a spatial structure that remains stable during the crowd motion. This structure differs depending on the value of n , for the consecutive n th -nearest-neighbor position set. The preferred position for the first-nearest neighbor is on the side of the pedestrian, while for further neighbors, this preference shifts to the axis of movement. The velocity correlations vary with the angle formed by the pair of neighboring pedestrians and the direction of motion and with the time delay between pedestrians' movements. The delay dependence of the correlations shows characteristic oscillations, produced by the velocity oscillations when striding; however, a filtering of the main frequency of individual striding out reduces the oscillations only partially. We conclude that pedestrians select their path directions so as to evade the necessity of continuously adjusting their speed to their neighbors'. They try to keep a given distance, but follow the person in front of them, as well as accepting and observing pedestrians on their sides. Additionally, we show an empirical example that illustrates the shape of a pedestrian's personal space during movement.

Angular momenta of fission fragments in the {alpha}-accompanied fission of {sup 252}Cf

Energy Technology Data Exchange (ETDEWEB)

Jandel, M.; Kliman, J.; Krupa, L.; Morhac, M. [Slovak Academy of Sciences, Department of Nuclear Physics, Bratislava (Slovakia); Joint Institute for Nuclear Research, Flerov Laboratory for Nuclear Reactions, Dubna (Russian Federation); Hamilton, J.H.; Kormicki, J.; Ramayya, A.V.; Hwang, J.K.; Luo, Y.X.; Fong, D.; Gore, P. [Vanderbilt University, Department of Physics, Nashville, TN (United States); Ter-Akopian, G.M.; Oganessian, Yu.Ts.; Rodin, A.M.; Fomichev, A.S.; Popeko, G.S. [Joint Institute for Nuclear Research, Flerov Laboratory for Nuclear Reactions, Dubna (Russian Federation); Daniel, A.V. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Rasmussen, J.O.; Macchiavelli, A.O.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Donangelo, R.; Cole, J.D.

2005-06-01

For the first time, average angular momenta of the ternary fission fragments {sup 100,102}Zr, {sup 106}Mo, {sup 144,146}Ba and {sup 138,140,142}Xe from the {alpha}-accompanied fission of {sup 252}Cf were obtained from relative intensities of prompt {gamma}-ray transitions with the use of the statistical model calculation. Average values of the angular momenta were compared with the corresponding values for the same fission fragments from the binary fission of {sup 252}Cf. Results indicate the presence of a decreasing trend in the average values of angular momenta induced in ternary fission fragments compared to the same binary fission fragments. On the average, the total angular momentum extracted for ternary fission fragments is {proportional_to}1.4{Dirac_h} lower than in binary fission. Consequently, results indicate that the mechanism of the ternary {alpha}-particles emission may directly effect an induction of angular momenta of fission fragments, and possible scenarios of such mechanisms are discussed. Further, the dependence of the angular momenta of {sup 106}Mo and {sup 140}Xe on the number of emitted neutrons from correlated pairs of primary fragments was obtained also showing a decreasing dependence of average angular momenta with increasing number of emitted neutrons. Consequences are briefly discussed. (orig.)

Design, Development and Testing of a Semicircular Type Capacitive Angular Position Sensor

Directory of Open Access Journals (Sweden)

Nikhil GAURAV

2011-06-01

Full Text Available A low cost semicircular type capacitive angular position sensor has been designed, developed and tested. It is made of two semicircular parallel plates where one plate is fixed and another plate is connected with the rotor whose angular position is to be measured. When the angular position of the rotor changes with respect to the fixed plate, the overlapping area between the two plates of the capacitor is varied causing a change in capacitance value. Capacitance variation obtained due to the change in angular position is in the nano farad range. For signal conditioning, series R-L-C resonating circuit instead of conventional bridge circuit has been used to convert the sensor capacitance variation in to voltage. Experimental result shows that the capacitance for change in angular position 0º-180º increases linearly and for 180º-360º it decreases linearly. To get a linearly increasing response of same slope for the full scale of 0º-360º, a suitable linearising circuit has been designed, developed and tested. Sensor output along with the signal conditioning shows good linearity and repeatability.

Quality of the restricted variation after projection method with angular momentum projection

International Nuclear Information System (INIS)

Rodriguez, Tomas R.; Egido, J.L.; Robledo, L.M.; Rodriguez-Guzman, R.

2005-01-01

Recently, the restricted angular momentum variation after projection method, using the quadrupole degree of freedom as a variational coordinate in conjunction with effective interactions of the Skyrme or Gogny type, has been used very successfully to study a variety of phenomena concerning the quadrupole degree of freedom. In this paper, we study the quality of such an approach by considering additional degrees of freedom as variational coordinates: the hexadecapole moment and the fluctuations on the quadrupole moment, particle number, and angular momentum operators. The study has been performed with the Gogny interaction (D1S parametrization) for the nuclei 32 Mg and 34 Mg. The results of the angular momentum projection and the subsequent generator coordinate calculations show that the extra degrees of freedom considered are irrelevant for the description of the lowest lying states for each angular momentum

Spatial and Angular Resolution Enhancement of Light Fields Using Convolutional Neural Networks

Science.gov (United States)

Gul, M. Shahzeb Khan; Gunturk, Bahadir K.

2018-05-01

Light field imaging extends the traditional photography by capturing both spatial and angular distribution of light, which enables new capabilities, including post-capture refocusing, post-capture aperture control, and depth estimation from a single shot. Micro-lens array (MLA) based light field cameras offer a cost-effective approach to capture light field. A major drawback of MLA based light field cameras is low spatial resolution, which is due to the fact that a single image sensor is shared to capture both spatial and angular information. In this paper, we present a learning based light field enhancement approach. Both spatial and angular resolution of captured light field is enhanced using convolutional neural networks. The proposed method is tested with real light field data captured with a Lytro light field camera, clearly demonstrating spatial and angular resolution improvement.

Angular distribution of ejected electrons from 20 keV He+ impact on He

International Nuclear Information System (INIS)

Tokoro, N.; Takenouchi, S.; Urakawa, J.; Oda, N.

1982-01-01

The angular distributions of ejected electrons in the energy range 5-70 eV have been measured at angles from 30 to 150 0 for 20 keV He + impact on He. The angular dependence of excitation cross sections of autoionisation states 2s 2 1 S and 2p 2 1 D+2s2p 1 P are in good agreement with previous data measured by Bordenave-Montesquieu et al (Phys. Rev.; A25:245 (1982)). The continuous parts of the electron spectra show symmetrical angular distributions around 90 0 in the laboratory frame for low-energy electrons (< approximately equal to 30 eV). These angular distributions are discussed in connection with the molecular autoionisation mechanism. (author)

Analytical scheme calculations of angular momentum coupling and recoupling coefficients

Science.gov (United States)

Deveikis, A.; Kuznecovas, A.

2007-03-01

We investigate the Scheme programming language opportunities to analytically calculate the Clebsch-Gordan coefficients, Wigner 6j and 9j symbols, and general recoupling coefficients that are used in the quantum theory of angular momentum. The considered coefficients are calculated by a direct evaluation of the sum formulas. The calculation results for large values of quantum angular momenta were compared with analogous calculations with FORTRAN and Java programming languages.

Analytical scheme calculations of angular momentum coupling and recoupling coefficients

International Nuclear Information System (INIS)

Deveikis, A.; Kuznecovas, A.

2007-01-01

We investigate the Scheme programming language opportunities to analytically calculate the Clebsch-Gordan coefficients, Wigner 6j and 9j symbols, and general recoupling coefficients that are used in the quantum theory of angular momentum. The considered coefficients are calculated by a direct evaluation of the sum formulas. The calculation results for large values of quantum angular momenta were compared with analogous calculations with FORTRAN and Java programming languages

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

Referencing geostrophic velocities using ADCP data Referencing geostrophic velocities using ADCP data

Directory of Open Access Journals (Sweden)

Isis Comas-Rodríguez

2010-06-01

Full Text Available Acoustic Doppler Current Profilers (ADCPs have proven to be a useful oceanographic tool in the study of ocean dynamics. Data from D279, a transatlantic hydrographic cruise carried out in spring 2004 along 24.5°N, were processed, and lowered ADCP (LADCP bottom track data were used to assess the choice of reference velocity for geostrophic calculations. The reference velocities from different combinations of ADCP data were compared to one another and a reference velocity was chosen based on the LADCP data. The barotropic tidal component was subtracted to provide a final reference velocity estimated by LADCP data. The results of the velocity fields are also shown. Further studies involving inverse solutions will include the reference velocity calculated here.

Free-surface velocity measurements using an optically recording velocity interferometer

International Nuclear Information System (INIS)

Lu Jianxin; Wang Zhao; Liang Jing; Shan Yusheng; Zhou Chuangzhi; Xiang Yihuai; Lu Ze; Tang Xiuzhang

2006-01-01

An optically recording velocity interferometer system (ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called 'Heaven I' with laser wavelength of 248.4 nm, pulse duration of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24 x 10 11 W·cm -2 , and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intensity 7.28 x 10 11 W·cm -2 . (authors)

On linear relationship between shock velocity and particle velocity

International Nuclear Information System (INIS)

Dandache, H.

1986-11-01

We attempt to derive the linear relationship between shock velocity U s and particle velocity U p from thermodynamic considerations, taking into account an ideal gas equation of state and a Mie-Grueneisen equation of state for solids. 23 refs

Angular analysis of charged and neutral B -> K mu(+) mu(-) decays

NARCIS (Netherlands)

Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Anderson, J.; Andreassen, R.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Balagura, V.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Bauer, Th.; Bay, A.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Belogurov, S.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Onderwater, G.; Pellegrino, A.

2014-01-01

The angular distributions of the rare decays B+ -> K+mu(+)mu(-) and B-0 -> K-S(0)mu(+)mu(-) are studied with data corresponding to 3 fb(-1) of integrated luminosity, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies with the LHCb detector. The angular distribution is

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.

Variation of level density parameter with angular momentum in 119Sb

International Nuclear Information System (INIS)

Aggarwal, Mamta; Kailas, S.

2015-01-01

Nuclear level density (NLD), a basic ingredient of Statistical Model has been a subject of interest for various decades as it plays an important role in the understanding of a wide variety of Nuclear reactions. There have been various efforts towards the precise determination of NLD and study its dependence on excitation energy and angular momentum as it is crucial in the determination of cross-sections. Here we report our results of theoretical calculations in a microscopic framework to understand the experimental results on inverse level density parameter (k) extracted for different angular momentum regions for 119 Sb corresponding to different γ-ray multiplicities by comparing the experimental neutron energy spectra with statistical model predictions where an increase in the level density with the increasing angular momentum is predicted. NLD and neutron emission spectra dependence on temperature and spin has been studied in our earlier works where the influence of structural transitions due to angular momentum and temperature on level density of states and neutron emission probability was shown

Determination of the filtration velocities and mean velocity in ground waters using radiotracers

International Nuclear Information System (INIS)

Duran P, Oscar; Diaz V, Francisco; Heresi M, Nelida

1994-01-01

An experimental method to determine filtration, or, Darcy velocity and mean velocity in underground waters using radiotracers, is described. After selecting the most appropriate tracers, from 6 chemical compounds, to measure water velocity, a method to measure filtration velocity was developed. By fully labelling the water column with 2 radioisotopes, Br and tritium, almost identical values were obtained for the aquifer filtration velocity in the sounding S1. This value was 0.04 m/d. Field porosity was calculated at 11% and mean velocity at 0.37 m.d. With the filtration velocity value and knowing the hydraulic variation between the soundings S1 and S2 placed at 10 meters, field permeability was estimated at 2.4 x 10 m/s. (author)

Time-dependent angular distribution of sputtered particles from amorphous targets

International Nuclear Information System (INIS)

Yamamura, Yasunori

1990-01-01

Using the time-evolution computer simulation code DYACAT, the time-dependent behavior of sputtering phenomena has been investigated. The DYACAT program is based on the binary collision approximation, and the cascade development in solids is followed time-evolutionally. The total sputtering yield, the angular distribution and the energy distribution of sputtered atoms are calculated as a function of time for 1 keV Ar→Cu, where the angle of incidence is the inverse surface normal. It is found that the angular distribution of the prompt collisional phase of the sputtering process shows an under-cosine and that the corresponding energy spectrum has a peak near 10 eV. The slow collisional phase of 1 keV Ar→Cu will start after 3x10 -14 s, and its angular distribution shows an over-cosine distribution. (orig.)

Radial velocity asymmetries from jets with variable velocity profiles

International Nuclear Information System (INIS)

Cerqueira, A. H.; Vasconcelos, M. J.; Velazquez, P. F.; Raga, A. C.; De Colle, F.

2006-01-01

We have computed a set of 3-D numerical simulations of radiatively cooling jets including variabilities in both the ejection direction (precession) and the jet velocity (intermittence), using the Yguazu-a code. In order to investigate the effects of jet rotation on the shape of the line profiles, we also introduce an initial toroidal rotation velocity profile. Since the Yguazu-a code includes an atomic/ionic network, we are able to compute the emission coefficients for several emission lines, and we generate line profiles for the Hα, [O I]λ6300, [S II]λ6716 and [N II]λ6548 lines. Using initial parameters that are suitable for the DG Tau microjet, we show that the computed radial velocity shift for the medium-velocity component of the line profile as a function of distance from the jet axis is strikingly similar for rotating and non-rotating jet models

Existence of black holes due to concentration of angular momentum

Energy Technology Data Exchange (ETDEWEB)

Khuri, Marcus A. [Department of Mathematics, Stony Brook University,Stony Brook, NY 11794 (United States)

2015-06-29

We present a general sufficient condition for the formation of black holes due to concentration of angular momentum. This is expressed in the form of a universal inequality, relating the size and angular momentum of bodies, and is proven in the context of axisymmetric initial data sets for the Einstein equations which satisfy an appropriate energy condition. A brief comparison is also made with more traditional black hole existence criteria based on concentration of mass.

Angular integration and inter-projection correlation effects in CT reconstruction

International Nuclear Information System (INIS)

Crawford, C.R.; Pele, N.J.

1987-01-01

CT reconstruction algorithms require snap-shot projections of an object. In order to minimize scan times, CT scanners rotate continuously which, in turn, prevents the acquisition of snap-shot projections. Acquired projections are integrals over angular position and may be correlated inter-projection. This paper shows that angular integration and inter-projection correlation introduce a radially dependent degradation of the spatial resolution and cause the image noise to vary non-linearly with radial position

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

Angular dependence of shallow dose

International Nuclear Information System (INIS)

Alvarez, J.L.

1986-01-01

The theoretical response of a detector is discussed and compared to measurements of shallow dose with tissue and phantom response detectors. A definite energy dependent angular response of dose and measurement was observed which could not be explained by simple trigonometric arguments. The response is back scatter dependent and must be considered in detector design and dose measurements. It is not possible for standard detectors to follow this response

A framework for simulating ultrasound imaging based on first order nonlinear pressure–velocity relations

DEFF Research Database (Denmark)

Du, Yigang; Fan, Rui; Li, Yong

2016-01-01

An ultrasound imaging framework modeled with the first order nonlinear pressure–velocity relations (NPVR) based simulation and implemented by a half-time staggered solution and pseudospectral method is presented in this paper. The framework is capable of simulating linear and nonlinear ultrasound...... propagation and reflections in a heterogeneous medium with different sound speeds and densities. It can be initialized with arbitrary focus, excitation and apodization for multiple individual channels in both 2D and 3D spatial fields. The simulated channel data can be generated using this framework......, and ultrasound image can be obtained by beamforming the simulated channel data. Various results simulated by different algorithms are illustrated for comparisons. The root mean square (RMS) errors for each compared pulses are calculated. The linear propagation is validated by an angular spectrum approach (ASA...

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)

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)

New method for evaluation of cervical vertebral maturation based on angular measurements.

Science.gov (United States)

Alhadlaq, Adel M; Al-Shayea, Eman I

2013-04-01

To investigate the validity of a new approach to assess the cervical vertebral maturation based on angular measurements of the lower border concavity of cervical vertebral bodies. Hand-wrist and lateral cephalometric radiographs of 197 male subjects with age range of 10-15 years attending the orthodontic clinic at King Saud University, Riyadh, Kingdom of Saudi Arabia were utilized. The study was carried out between September 2009 and May 2011. The study sample was divided into 6 groups (group 1: 10 years to group 6: 15 years) based on the chronological age of the subject. The skeletal age of the subjects was determined using Greulich and Pyle's standard radiographic atlas, and skeletal maturation was assessed by Fishman's skeletal maturity indicators. The cervical vertebral maturation (CVM) of subjects was determined using angular measurements of the second, third, and fourth cervical vertebral bodies. The validity of the newly developed method was assessed by examining the correlation between CVM stages determined by the angular measurements and the skeletal maturation level as determined by the standard hand-wrist methods. A significant correlation (r=0.94) was found between the angular CVM stages and the skeletal age determined by Greulich and Pyle's atlas from hand-wrist radiographs. Also, a high correlation (r=0.94) was found between the angular CVM stages and the Fishman's hand-wrist skeletal maturity indicators. The new angular measurement approach to determine CVM is valid and has the potential to be applied in assessing skeletal maturity level in growing male children.

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

Energy Technology Data Exchange (ETDEWEB)

Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim, E-mail: ekarimi@uottawa.ca [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Boyd, Robert W. [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

2014-09-08

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

International Nuclear Information System (INIS)

Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim; Boyd, Robert W.

2014-01-01

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

Mitigation of radiation-pressure-induced angular instability of a Fabry–Perot cavity consisting of suspended mirrors

Energy Technology Data Exchange (ETDEWEB)

Nagano, Koji, E-mail: knagano@icrr.u-tokyo.ac.jp [KAGRA Observatory, Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582 (Japan); Enomoto, Yutaro; Nakano, Masayuki [KAGRA Observatory, Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582 (Japan); Furusawa, Akira [Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Kawamura, Seiji [KAGRA Observatory, Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582 (Japan)

2016-12-01

To observe radiation pressure noise in optical cavities consisting of suspended mirrors, high laser power is necessary. However, because the radiation pressure on the mirrors could cause an angular anti-spring effect, the high laser power could induce angular instability to the cavity. An angular control system using radiation pressure as an actuator, which was previously invented to reduce the anti-spring effect for the low power case, was applied to the higher power case where the angular instability would occur. As a result the angular instability was mitigated. It was also demonstrated that the cavity was unstable without this control system. - Highlights: • High laser power could cause angular instability to a suspended Fabry–Perot cavity. • To mitigate the instability, the control system using radiation pressure is applied. • Mitigating the radiation-pressure-induced angular instability is demonstrated. • It is also confirmed that the cavity would be unstable without the control system.

Angular distributions of intermediate mass fragments emitted in 30 MeV/u 40Ar induced reactions

International Nuclear Information System (INIS)

Gou Quanbu; Zhu Yongtai; Xu Hushan; Wei Zhiyong; Lu Jun; Zhang Yuhu; Wang Qi; Li Songlin; Wu Zhongli

1999-01-01

The angular distributions of intermediate mass fragments with charge numbers from 3 to 24 emitted in 30 MeV/u 40 Ar + 58,64 Ni and 115 In reactions over an angular range of 5 degree-140 degree have been measured. In different angular region an exponential distribution function dσ/dΩ = N exp(-θ/α) was used to fit the measured angular distributions. The decay factor α which can be connected with the interaction time τ and the factor N which is related to the intensity of the emission sources have been extracted. The relationship of α(Z) and N(Z) with Z for different reaction systems and different angular regions has been discussed. The different behavior of dσ/dΩ, α(Z), and N(Z) for the three studied reaction systems exists mainly in the middle and backward angular regions. The dependencies of angular distributions on isospin and the size of reaction systems have also been discussed

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

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%

The γ-ray angular distribution in fast neutron inelastic scattering from iron

Science.gov (United States)

Beyer, Roland; Dietz, Mirco; Bemmerer, Daniel; Junghans, Arnd R.; Kögler, Toni; Massarczyk, Ralph; Müller, Stefan; Schmidt, Konrad; Schwengner, Ronald; Szücs, Tamás; Takács, Marcell P.; Wagner, Andreas

2018-04-01

The angular distribution of γ-rays emitted after inelastic scattering of fast neutrons from iron was determined at the n ELBE neutron time-of-flight facility. An iron sample of natural isotopic composition was irradiated by a continuous photo-neutron spectrum in the energy range from about 0.1 up to 10 MeV. The de-excitation γ-rays of the four lowest excited states of 56Fe and the first excited state of 54Fe were detected using a setup of five high-purity germanium (HPGe) detectors and five LaBr3 scintillation detectors positioned around the sample at 30°, 55°, 90°, 125° and 150° with respect to the incoming neutron beam. The resulting angular distributions were fitted by Legendre polynomials up to 4th order and the angular distribution coefficients a2 and a4 were extracted. The angular distribution coefficients of three transitions in 56Fe are reported here for the first time. The results are applied to a previous measurement of the inelastic scattering cross section determined using a single HPGe detector positioned at 125°. Using the updated γ-ray angular distribution, the previous cross section results are in good agreement with reference data.

Semiclassical analysis of the Wigner 12j symbol with one small angular momentum

International Nuclear Information System (INIS)

Yu Liang

2011-01-01

We derive an asymptotic formula for the Wigner 12j symbol, in the limit of one small and 11 large angular momenta. There are two kinds of asymptotic formulas for the 12j symbol with one small angular momentum. We present the first kind of formula in this paper. Our derivation relies on the techniques developed in the semiclassical analysis of the Wigner 9j symbol [L. Yu and R. G. Littlejohn, Phys. Rev. A 83, 052114 (2011)], where we used a gauge-invariant form of the multicomponent WKB wave functions to derive asymptotic formulas for the 9j symbol with small and large angular momenta. When applying the same technique to the 12j symbol in this paper, we find that the spinor is diagonalized in the direction of an intermediate angular momentum. In addition, we find that the geometry of the derived asymptotic formula for the 12j symbol is expressed in terms of the vector diagram for a 9j symbol. This illustrates a general geometric connection between asymptotic limits of the various 3nj symbols. This work contributes an asymptotic formula for the 12j symbol to the quantum theory of angular momentum, and serves as a basis for finding asymptotic formulas for the Wigner 15j symbol with two small angular momenta.

Estudo radiológico do valor angular da cifose torácica em adolescentes Estudio radiológico del valor angular de la cifosis torácica en adolescentes Radiological study of the angular value of thoracic kyphosis in adolescents

Directory of Open Access Journals (Sweden)

Juan Javier Moreira Moreira

2010-12-01

Full Text Available OBJETIVO: determinar a diferença dos valores angulares da cifose torácica utilizando como vértebra terminal cranial diferentes níveis (T2 a T5. MÉTODOS: foram avaliadas radiografias em perfil de cem adolescentes voluntários saudáveis da Escola Industrial do Serviço Social da Indústria (SESI de Ribeirão Preto (SP, com prévia autorização dos pais ou responsáveis. Foram excluídas as radiografias de dez indivíduos por falhas na qualidade. Os parâmetros avaliados foram: mensuração da cifose torácica pelo método de Cobb, utilizando T2, T3, T4 ou T5 como vértebra terminal cranial e T12 como vértebra terminal caudal. RESULTADOS: foram avaliados 90 indivíduos (46 do sexo masculino e 44 do feminino, com idade variando de 13 a 15 anos (média 14±6. O valor angular da cifose torácica nos diferentes níveis variou entre 45º (T2-T12 e 35º (T5-T12 no sexo masculino, e valor angular entre 43º(T2-T12 e 30º (T5-T12 no sexo feminino. CONCLUSÃO: foi observada diferença constante de aproximadamente 5º quando comparados os valores angulares da cifose torácica utilizando diferentes níveis (T2 a T5 como vértebra terminal cranial.OBJETIVO: determinar la diferencia de los valores angulares de la cifosis torácica usando como vértebra terminal craneal, diferentes niveles (T2 a T5. MÉTODOS: fueron evaluadas radiografías en perfil de cien adolescentes voluntarios saludables de la Escola Industrial do Serviço Social da Indústria (SESI de Ribeirão Preto (SP, con previa autorización de sus padres o responsables. Fueron excluidas radiografías de diez individuos por fallas de resolución. Los parámetros evaluados fueron: la medida de la cifosis torácica por el método de Cobb, usando T2,T3,T4 y T5 como vértebra terminal craneal y T12 como vértebra terminal caudal. RESULTADOS: fueron evaluados 90 individuos (46 hombres y 44 mujeres, con edades que varían de 13 a 15 años (media 14±6. El valor angular de la cifosis torácica en los

Whole-body angular momentum during stair walking using passive and powered lower-limb prostheses.

Science.gov (United States)

Pickle, Nathaniel T; Wilken, Jason M; Aldridge, Jennifer M; Neptune, Richard R; Silverman, Anne K

2014-10-17

Individuals with a unilateral transtibial amputation have a greater risk of falling compared to able-bodied individuals, and falling on stairs can lead to serious injuries. Individuals with transtibial amputations have lost ankle plantarflexor muscle function, which is critical for regulating whole-body angular momentum to maintain dynamic balance. Recently, powered prostheses have been designed to provide active ankle power generation with the goal of restoring biological ankle function. However, the effects of using a powered prosthesis on the regulation of whole-body angular momentum are unknown. The purpose of this study was to use angular momentum to evaluate dynamic balance in individuals with a transtibial amputation using powered and passive prostheses relative to able-bodied individuals during stair ascent and descent. Ground reaction forces, external moment arms, and joint powers were also investigated to interpret the angular momentum results. A key result was that individuals with an amputation had a larger range of sagittal-plane angular momentum during prosthetic limb stance compared to able-bodied individuals during stair ascent. There were no significant differences in the frontal, transverse, or sagittal-plane ranges of angular momentum or maximum magnitude of the angular momentum vector between the passive and powered prostheses during stair ascent or descent. These results indicate that individuals with an amputation have altered angular momentum trajectories during stair walking compared to able-bodied individuals, which may contribute to an increased fall risk. The results also suggest that a powered prosthesis provides no distinct advantage over a passive prosthesis in maintaining dynamic balance during stair walking. Copyright © 2014 Elsevier Ltd. All rights reserved.

Propagation of the Semidiurnal Internal Tide: Phase Velocity Versus Group Velocity

Science.gov (United States)

Zhao, Zhongxiang

2017-12-01

The superposition of two waves of slightly different wavelengths has long been used to illustrate the distinction between phase velocity and group velocity. The first-mode M2 and S2 internal tides exemplify such a two-wave model in the natural ocean. The M2 and S2 tidal frequencies are 1.932 and 2 cycles per day, respectively, and their superposition forms a spring-neap cycle in the semidiurnal band. The spring-neap cycle acts like a wave, with its frequency, wave number, and phase being the differences of the M2 and S2 internal tides. The spring-neap cycle and energy of the semidiurnal internal tide propagate at the group velocity. Long-range propagation of M2 and S2 internal tides in the North Pacific is observed by satellite altimetry. Along a 3,400 km beam spanning 24°-54°N, the M2 and S2 travel times are 10.9 and 11.2 days, respectively. For comparison, it takes the spring-neap cycle 21.1 days to travel over this distance. Spatial maps of the M2 phase velocity, the S2 phase velocity, and the group velocity are determined from phase gradients of the corresponding satellite observed internal tide fields. The observed phase and group velocities agree with theoretical values estimated using the World Ocean Atlas 2013 annual-mean ocean stratification.

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

Spin and intrinsic angular momentum; application to the electromagnetic field

International Nuclear Information System (INIS)

Paillere, P.

1993-05-01

Within the framework of the field theory governed by a Lagrangian, function of the tensor quantities and their covariant first derivatives, and starting with the third order intrinsic angular momentum tensor obtained from a variational principle, the intrinsic angular momentum vector of the electromagnetic field in vacuum is determined. This expression leads to spin matrices for the electromagnetic field, with unity as eigenvalue, thus allowing to bridge the gap between continuous physics and quantum physics. 6 refs

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...

Angular dependence of response of dosimeters exposed to an extended radioactive source

International Nuclear Information System (INIS)

Manai, K.; Trabelsi, A.; Madouri, F.

2014-01-01

This study was carried out to investigate the exposure angular dependence of dosimeters response when exposed to the extended gamma source of an irradiation facility. Using analytical and Monte Carlo analysis, we show that dosimeters response has no angular dependence as claimed by a previous study. The dose rate formula we derived takes into account the path length of the photons in the dosimeter. Experimental data have been used to validate our analytical and Monte Carlo methods. Furthermore, the effects on the dosimeters responses in relation to their sizes response of their size and geometry and orientation have been investigated and, within statistical errors, no angular dependence was found. - Highlights: • We investigate the exposer angle dependence of dosimeter response to a gamma source. • Analytical and Monte Carlo analyses show no angular dependence as claimed by others. • We derive the dose rate formulae taking into account the path length of photons. • Analytical and Monte Carlo models have been validated using experimental data

Determination of velocity correction factors for real-time air velocity monitoring in underground mines.

Science.gov (United States)

Zhou, Lihong; Yuan, Liming; Thomas, Rick; Iannacchione, Anthony

2017-12-01

When there are installations of air velocity sensors in the mining industry for real-time airflow monitoring, a problem exists with how the monitored air velocity at a fixed location corresponds to the average air velocity, which is used to determine the volume flow rate of air in an entry with the cross-sectional area. Correction factors have been practically employed to convert a measured centerline air velocity to the average air velocity. However, studies on the recommended correction factors of the sensor-measured air velocity to the average air velocity at cross sections are still lacking. A comprehensive airflow measurement was made at the Safety Research Coal Mine, Bruceton, PA, using three measuring methods including single-point reading, moving traverse, and fixed-point traverse. The air velocity distribution at each measuring station was analyzed using an air velocity contour map generated with Surfer ® . The correction factors at each measuring station for both the centerline and the sensor location were calculated and are discussed.

The angular gamma flux in an iron slab shield

International Nuclear Information System (INIS)

Penkuhn, H.

1975-08-01

The angular distribution of the photon energy and dose rate flux in a plane iron shield is investigated assuming an isotropic volume source. Near the shield axis (cos phi approximately 1, with phi=angle between shield axis and gamma direction) the angular spectrum is strongly space-dependent. For large phi, space-independent fits are given. Source energies from 0.662 to 6 MeV and penetrations from 6 to 60 cm are treated and the results are compared with a similar investigation on normal concrete. The differences iron-concrete are appreciable only for the lowest source energy

Uncertainty assessment of 3D instantaneous velocity model from stack velocities

Science.gov (United States)

Emanuele Maesano, Francesco; D'Ambrogi, Chiara

2015-04-01

3D modelling is a powerful tool that is experiencing increasing applications in data analysis and dissemination. At the same time the need of quantitative uncertainty evaluation is strongly requested in many aspects of the geological sciences and by the stakeholders. In many cases the starting point for 3D model building is the interpretation of seismic profiles that provide indirect information about the geology of the subsurface in the domain of time. The most problematic step in the 3D modelling construction is the conversion of the horizons and faults interpreted in time domain to the depth domain. In this step the dominant variable that could lead to significantly different results is the velocity. The knowledge of the subsurface velocities is related mainly to punctual data (sonic logs) that are often sparsely distributed in the areas covered by the seismic interpretation. The extrapolation of velocity information to wide extended horizons is thus a critical step to obtain a 3D model in depth that can be used for predictive purpose. In the EU-funded GeoMol Project, the availability of a dense network of seismic lines (confidentially provided by ENI S.p.A.) in the Central Po Plain, is paired with the presence of 136 well logs, but few of them have sonic logs and in some portion of the area the wells are very widely spaced. The depth conversion of the 3D model in time domain has been performed testing different strategies for the use and the interpolation of velocity data. The final model has been obtained using a 4 layer cake 3D instantaneous velocity model that considers both the initial velocity (v0) in every reference horizon and the gradient of velocity variation with depth (k). Using this method it is possible to consider the geological constraint given by the geometries of the horizons and the geo-statistical approach to the interpolation of velocities and gradient. Here we present an experiment based on the use of set of pseudo-wells obtained from the

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

Velocity Feedback Experiments

Directory of Open Access Journals (Sweden)

Chiu Choi

2017-02-01

Full Text Available Transient response such as ringing in a control system can be reduced or removed by velocity feedback. It is a useful control technique that should be covered in the relevant engineering laboratory courses. We developed velocity feedback experiments using two different low cost technologies, viz., operational amplifiers and microcontrollers. These experiments can be easily integrated into laboratory courses on feedback control systems or microcontroller applications. The intent of developing these experiments was to illustrate the ringing problem and to offer effective, low cost solutions for removing such problem. In this paper the pedagogical approach for these velocity feedback experiments was described. The advantages and disadvantages of the two different implementation of velocity feedback were discussed also.

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

Generation of vertical angular momentum in single, double, and triple-turn pirouette en dehors in ballet.

Science.gov (United States)

Kim, Jemin; Wilson, Margaret A; Singhal, Kunal; Gamblin, Sarah; Suh, Cha-Young; Kwon, Young-Hoo

2014-09-01

The purpose of this study was to investigate the vertical angular momentum generation strategies used by skilled ballet dancers in pirouette en dehors. Select kinematic parameters of the pirouette preparation (stance depth, vertical center-of-mass motion range, initial shoulder line position, shoulder line angular displacement, and maximum trunk twist angle) along with vertical angular momentum parameters during the turn (maximum momentums of the whole body and body parts, and duration and rate of generation) were obtained from nine skilled collegiate ballet dancers through a three-dimensional motion analysis and compared among three turn conditions (single, double, and triple). A one-way ('turn') multivariate analysis of variance of the kinematic parameters and angular momentum parameters of the whole body and a two-way analysis of variance ('turn' × 'body') of the maximum angular momentums of the body parts were conducted. Significant 'turn' effects were observed in the kinematic/angular momentum parameters (both the preparation and the turn) (p <  0.05). As the number of turns increased, skilled dancers generated larger vertical angular momentums by predominantly increasing the rate of momentum generation using rotation of the upper trunk and arms. The trail (closing) arm showed the largest contribution to whole-body angular momentum followed by the lead arm.

Di-jet production and angular correlations in DIS at NLO

International Nuclear Information System (INIS)

Jaliflian-Marian, J.

2016-01-01

Angular correlations are a sensitive probe of the dynamics of QCD at high energy. In particular azimuthal angular correlations between two hadrons produced in Deeply Inelastic Scattering (DIS) of a virtual photon on a hadron or nucleus offer the best environment in which to investigate high gluon density (gluon saturation) effects expected to arise at small x. Here we give a progress report on our derivation of Next to Leading Order (NLO) corrections to di-jet (di-hadron) production in DIS. (author)

Orbital and angular motion construction for low thrust interplanetary flight

Science.gov (United States)

Yelnikov, R. V.; Mashtakov, Y. V.; Ovchinnikov, M. Yu.; Tkachev, S. S.

2016-11-01

Low thrust interplanetary flight is considered. Firstly, the fuel-optimal control is found. Then the angular motion is synthesized. This motion provides the thruster tracking of the required by optimal control direction. And, finally, reaction wheel control law for tracking this angular motion is proposed and implemented. The numerical example is given and total operation time for thrusters is found. Disturbances from solar pressure, thrust eccentricity, inaccuracy of reaction wheels installation and errors of inertia tensor are taken into account.

On the angular distributions of the heavy products of (HI, xn) reactions

International Nuclear Information System (INIS)

Sagajdak, R.N.

1989-01-01

The effects of neutron evaporation and scattering in the target on the angular distribution of the heavy products of (HI, xn) reactions is considered. Based on the analysis of the experimental angular distributions and their calculated parameters a simple phenomenological approach to the description of these distributions is proposed. The calculated distributions are compared with the experimental ones cited in the literature. The possibilities of using the proposed approach to calculate the integrated angular distributions of heavy products and to determine the efficiency of collecting (HI, xn) reaction products under the conditions of the kinematic separation of recoil nuclei are outlined. 28 refs.; 9 figs

Combined spatial/angular domain decomposition SN algorithms for shared memory parallel machines

International Nuclear Information System (INIS)

Hunter, M.A.; Haghighat, A.

1993-01-01

Several parallel processing algorithms on the basis of spatial and angular domain decomposition methods are developed and incorporated into a two-dimensional discrete ordinates transport theory code. These algorithms divide the spatial and angular domains into independent subdomains so that the flux calculations within each subdomain can be processed simultaneously. Two spatial parallel algorithms (Block-Jacobi, red-black), one angular parallel algorithm (η-level), and their combinations are implemented on an eight processor CRAY Y-MP. Parallel performances of the algorithms are measured using a series of fixed source RZ geometry problems. Some of the results are also compared with those executed on an IBM 3090/600J machine. (orig.)

Simple method for evaluating Goldstone diagrams in an angular momentum coupled representation

International Nuclear Information System (INIS)

Kuo, T.T.S.; Shurpin, J.; Tam, K.C.; Osnes, E.; Ellis, P.J.

1981-01-01

A simple and convenient method is derived for evaluating linked Goldstone diagrams in an angular momentum coupled representation. Our method is general, and can be used to evaluate any effective interaction and/or effective operator diagrams for both closed-shell nuclei (vacuum to vacuum linked diagrams) and open-shell nuclei (valence linked diagrams). The techniques of decomposing diagrams into ladder diagrams, cutting open internal lines and cutting off one-body insertions are introduced. These enable us to determine angular momentum factors associated with diagrams in the coupled representation directly, without the need for carrying out complicated angular momentum algebra. A summary of diagram rules is given

Projection methods for the analysis of molecular-frame photoelectron angular distributions

International Nuclear Information System (INIS)

Grum-Grzhimailo, A.N.; Lucchese, R.R.; Liu, X.-J.; Pruemper, G.; Morishita, Y.; Saito, N.; Ueda, K.

2007-01-01

A projection method is developed for extracting the nondipole contribution from the molecular frame photoelectron angular distributions of linear molecules. A corresponding convenient parametric form for the angular distributions is derived. The analysis was performed for the N 1s photoionization of the NO molecule a few eV above the ionization threshold. No detectable nondipole contribution was found for the photon energy of 412 eV

There are many ways to spin a photon: Half-quantization of a total optical angular momentum.

Science.gov (United States)

Ballantine, Kyle E; Donegan, John F; Eastham, Paul R

2016-04-01

The angular momentum of light plays an important role in many areas, from optical trapping to quantum information. In the usual three-dimensional setting, the angular momentum quantum numbers of the photon are integers, in units of the Planck constant ħ . We show that, in reduced dimensions, photons can have a half-integer total angular momentum. We identify a new form of total angular momentum, carried by beams of light, comprising an unequal mixture of spin and orbital contributions. We demonstrate the half-integer quantization of this total angular momentum using noise measurements. We conclude that for light, as is known for electrons, reduced dimensionality allows new forms of quantization.

The velocity of sound

International Nuclear Information System (INIS)

Beyer, R.T.

1985-01-01

The paper reviews the work carried out on the velocity of sound in liquid alkali metals. The experimental methods to determine the velocity measurements are described. Tables are presented of reported data on the velocity of sound in lithium, sodium, potassium, rubidium and caesium. A formula is given for alkali metals, in which the sound velocity is a function of shear viscosity, atomic mass and atomic volume. (U.K.)

A study of semi-rigid support on ankle supination sprain kinematics.

Science.gov (United States)

Tang, Y M; Wu, Z H; Liao, W H; Chan, K M

2010-12-01

Ankle sprain injury is very common in sports and the use of ankle support is crucial. This research investigated the effect of an ankle brace in reducing the ankle angular displacement and angular velocity during sudden supination. In the experiment, 11 healthy males were tested. The bracing condition, semi-rigid ankle braces were investigated. The angular displacement and angular velocity of the ankle were computed. The motion-capture system was adopted to capture the three-dimensional coordinates of the reflective markers. The coordinates of the reflective markers were used to compute the ankle kinematics during simulated ankle supination. A mechanical supination platform was used to simulate the sprain motions. Experimental results showed that the semi-rigid brace tested significantly reduced the ankle angular displacement and angular velocity compared with control conditions during sudden supination. In conclusion, the semi-rigid-type brace can provide significant restriction to reduce the magnitudes of the angular displacement and angular velocity of the ankle during sudden supination sprain. The semi-rigid-type brace is suggested as the prophylactic bracing for the ankle. © 2009 John Wiley & Sons A/S.

Mechanical evidence of the orbital angular momentum to energy ratio of vortex beams.

Science.gov (United States)

Demore, Christine E M; Yang, Zhengyi; Volovick, Alexander; Cochran, Sandy; MacDonald, Michael P; Spalding, Gabriel C

2012-05-11

We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam's topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result.

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.

Energy spectrum and angular distribution of prompt cosmic-ray muons

Energy Technology Data Exchange (ETDEWEB)

Castagnoli, C; Picchi, P [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale); Castellina, A; D' Ettorre Piazzoli, B; Mannocchi, G; Vernetto, S [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica

1984-07-01

The energy spectrum and angular distribution of atmospheric prompt muons are calculated by using an integral solution for production of charmed particles, their decay and muon transport in the atmosphere. Current experimental information from accelerator and theoretical ideas about charm cross-section and semi-leptonic decay are used to give a reference prompt muon spectrum to compare with that from conventional sources (..pi.. and K decay). The obtained differential spectrum has an energy dependence which approaches that of the primary cosmic rays. The integral intensity of prompt muons is equal to the conventional one at about 250 TeV. The angular distribution is found to be practically flat in the range (0/80)/sup 0/ irrespective of the muon energy. On the basis of this analysis we estimate that accurate measurements of muon energy spectrum and angular distribution at energies greater than 10 TeV should allow one to obtain useful information regarding charm hadroproduction cross-section in the 100 TeV region.

Angular Magnetoresistance of Nanowires with Alternating Cobalt and Nickel Segments

KAUST Repository

Mohammed, Hanan; Corte-Leon, H.; Ivanov, Yurii P.; Moreno, J. A.; Kazakova, O.; Kosel, Jü rgen

2017-01-01

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.

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