5,842 research outputs found
Moving Signals and Their Measured Frequencies
In determining the classical Doppler Effect, two assumptions are used for
computing the difference in distance travelled by consecutive signals: (a) the
receptor is stationary, and (b) the emitter is stationary. The calculated
Doppler Effect under the two assumptions are identical, provided the velocity
of propagation with respect to source and the velocity of propagation with
respect to the receptor differ exactly by the velocity of relative motion. We
show that, in the case of light, the ratio of the two calculated classical
Doppler Effects, with propagation speed c in the source and receptor inertial
frames respectively, remains constant in all geometries and orientations.
Furthermore, the observed Doppler Effect, as predicted by special relativity,
is the geometric mean of the two expected classical Doppler Effects in all
geometries and orientations. This leads to two simultaneous conclusions: (1) by
the receptor that the clock associated with the emitter runs slow, and (2) by
the emitter that the clock associated with the receptor runs slow. These
differences can be resolved if we theorize that light travels at speed c with
respect to the emitter as it leaves the emitter and travels at speed c with
respect to the receptor as it approaches the receptor.Comment: Revised in accordance with peer review process; Published August 2013
in Int. J. Engg. Res. & Sci & Tech 2(3) pp 24-3
Relaxation Behavior by Time-Salt and Time-Temperature Superpositions of Polyelectrolyte Complexes from Coacervate to Precipitate
Complexation between anionic and cationic polyelectrolytes results in
solid-like precipitates or liquid-like coacervate depending on the added salt
in the aqueous medium. However, the boundary between these polymer-rich phases
is quite broad and the associated changes in the polymer relaxation in the
complexes across the transition regime are poorly understood. In this work, the
relaxation dynamics of complexes across this transition is probed over a wide
timescale by measuring viscoelastic spectra and zero-shear viscosities at
varying temperatures and salt concentrations for two different salt types. We
find that the complexes exhibit time-temperature superposition (TTS) at all
salt concentrations, while the range of overlapped-frequencies for
time-temperature-salt superposition (TTSS) strongly depends on the salt
concentration (Cs) and gradually shifts to higher frequencies as Cs is
decreased. The sticky-Rouse model describes the relaxation behavior at all Cs.
However, collective relaxation of polyelectrolyte complexes gradually
approaches a rubbery regime and eventually exhibits a gel-like response as Cs
is decreased and limits the validity of TTSS.Comment: 12 pages, 5 figures, Follow Gels journal link for latest versio
Differing perceptions on the landing of the rod into the slot
In the usual rod and slot paradox, the rod, if it falls, was expected to fall
into the slot due to gravity. Many thought experiments have been conducted
where the presence of gravity is eliminated with the rod and slot approaching
each other along a line joining their centers, whereby the considerations come
strictly under Special Relativity. In these experiments the line of motion is
not parallel to either the axis of the rod or the slot. In this paper we
consider in detail the two cases when the rod does fall into the slot and when
the rod does not fall into the slot, each from the perspective of the co-moving
frames of the rod and the slot. We show that whether the rod falls into the
slot as determined by Galilean kinematics is also valid under relativistic
kinematics; this determination does not depend upon the magnitude of the
velocity, but only on the proper lengths and the proper angles of the rod and
slot with the line of motion. Our conclusion emphasizes the fact that the
passing (or crashing) of the rod as a wholesome event is unaffected by
relativistic kinematics. We also provide a simple formula to determine whether
or not the rod passes through the slot.Comment: 9 pages, 6 figure
Comprehensive learning incorporating Ako – a tertiary education approach at Wintec
This article outlines the design and implementation of a scenario-based approach to teaching and learning in tertiary education, inspired from Ako, adopted at the Waikato Institute of Technology (Wintec). This learning approach, titled ‘Comprehensive Learning (CL)’, aligns with the holistic objective of enabling students with an active, flexible, personalised, authentic and practical approach to learning that builds upon students’ interests and experiences. The article explains the motivation and the process used in creating and applying this approach to teach some of the IT and Business modules. The main reason to implement this approach is to encourage/enable critical thinking while learning in a continuous and personalised manner. CL allows students to specialize in a context of their choice, which in turn induces learning. In addition, students are less motivated to plagiarize due to the unique nature of their scenarios, and inherent safeguards present within the approach
Comprehensive learning incorporating Ako: A tertiary education approach at Wintec
This article outlines the design and implementation of a scenario-based approach to teaching and learning in tertiary education, inspired from Ako, adopted at the Waikato Institute of Technology (Wintec). This learning approach, titled ‘Comprehensive Learning (CL)’, aligns with the holistic objective of enabling students with an active, flexible, personalised, authentic and practical approach to learning that builds upon students’ interests and experiences. The article explains the motivation and the process used in creating and applying this approach to teach some of the IT and Business modules. The main reason to implement this approach is to encourage/enable critical thinking while learning in a continuous and personalised manner. CL allows students to specialize in a context of their choice, which in turn induces learning. In addition, students are less motivated to plagiarize due to the unique nature of their scenarios, and inherent safeguards present within the approach
Fields and fluids on curved non-relativistic spacetimes
We consider non-relativistic curved geometries and argue that the background
structure should be generalized from that considered in previous works. In this
approach the derivative operator is defined by a Galilean spin connection
valued in the Lie algebra of the Galilean group. This includes the usual spin
connection plus an additional "boost connection" which parameterizes the
freedom in the derivative operator not fixed by torsion or metric
compatibility. As an example we write down the most general theory of
dissipative fluids consistent with the second law in curved non-relativistic
geometries and find significant differences in the allowed transport
coefficients from those found previously. Kubo formulas for all response
coefficients are presented. Our approach also immediately generalizes to
systems with independent mass and charge currents as would arise in
multicomponent fluids. Along the way we also discuss how to write general
locally Galilean invariant non-relativistic actions for multiple particle
species at any order in derivatives. A detailed review of the geometry and its
relation to non-relativistic limits may be found in a companion paper
[arXiv:1503.02682].Comment: Reference added. 44 page
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