3,768 research outputs found
Spectrometer
Ultraviolet spectrometer measures pure monochromatic wavelengths in predetermined narrow wave bands. Two stages are incorporated: stationary dispersed beam is intercepted by array of slits cut into plate at discrete wavelength locations; second stage is inverted spectrometer which recombines dispersed spectrum at single exit slit
Lunar nomenclature Interim report
Revised index of proposed names for craters on lunar far side with identifying bibliographical dat
MOVEMENT PATTERN CHANGES OF BASKETBALL JUMP SHOOTING IN RELATION TO DISTANCE BASED ON THE ANALYSIS OF TIME COURSES
The purpose of this study was to identify changes in movement patterns of basketball jump shooting in relation to distance based on the analysis of time courses. One experienced female player practised jump shots from 4, 5, and 6 m distance which were filmed in the sagittal plane. Cinematic parameters of three successful shots from each distance were analysed by process oriented methods. The hierarchical duster analysis divided the movement patterns in two main branches representing the shots of middle (4 m) and long (5-6 m) distance. The factor analysis s-technique identified different time courses for the angular velocity of the hip, shoulder and the orientation of the upper am. The results also indicate that process oriented methods represent a different quality of movement pattern analysis than methods based on time discrete variables
Collective motion of binary self-propelled particle mixtures
In this study, we investigate the phenomenon of collective motion in binary
mixtures of self-propelled particles. We consider two particle species, each of
which consisting of pointlike objects that propel with a velocity of constant
magnitude. Within each species, the particles try to achieve polar alignment of
their velocity vectors, whereas we analyze the cases of preferred polar,
antiparallel, as well as perpendicular alignment between particles of different
species. Our focus is on the effect that the interplay between the two species
has on the threshold densities for the onset of collective motion and on the
nature of the solutions above onset. For this purpose, we start from suitable
Langevin equations in the particle picture, from which we derive mean field
equations of the Fokker-Planck type and finally macroscopic continuum field
equations. We perform particle simulations of the Langevin equations, linear
stability analyses of the Fokker-Planck and macroscopic continuum equations,
and we numerically solve the Fokker-Planck equations. Both, spatially
homogeneous and inhomogeneous solutions are investigated, where the latter
correspond to stripe-like flocks of collectively moving particles. In general,
the interaction between the two species reduces the threshold density for the
onset of collective motion of each species. However, this interaction also
reduces the spatial organization in the stripe-like flocks. The most
interesting behavior is found for the case of preferred perpendicular alignment
between different species. There, a competition between polar and truly nematic
orientational ordering of the velocity vectors takes place within each particle
species. Finally, depending on the alignment rule for particles of different
species and within certain ranges of particle densities, identical and inverted
spatial density profiles can be found for the two particle species.Comment: 16 pages, 10 figure
Soft deformable self-propelled particles
In this work we investigate the collective behavior of self-propelled
particles that deform due to local pairwise interactions. We demonstrate that
this deformation alone can induce alignment of the velocity vectors. The onset
of collective motion is analyzed. Applying a Gaussian-core repulsion between
the particles, we find a transition to disordered non-collective motion under
compression. We here explain that this reflects the reentrant fluid behavior of
the general Gaussian-core model now applied to a self-propelled system.
Truncating the Gaussian potential can lead to cluster crystallization or more
disordered cluster states. For intermediate values of the Gaussian-core
potential we for the first time observe laning for deformable self-propelled
particles. Finally, without the core potential, but including orientational
noise, we connect our description to the Vicsek approach for self-propelled
particles with nematic alignment interactions.Comment: 6 pages, 7 figure
Development of lunar nomenclature
A system of unification and standardization for lunar nomenclature was developed. The following recommendations were made for use in future lunar cartography: (1) satellite craters, previously designated by letters will be named; (2) names will no longer be restricted to scientists, but will also include great contributors to human knowledge and human culture; and (3) a system of grids for dividing the moon into 144 regions and subdividing these regions into 2304 provinces will be used
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